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Class: SQLite3::Database

Relationships & Source Files
Namespace Children
Classes:
FunctionProxy
Super Chains via Extension / Inclusion / Inheritance
Instance Chain:
self, Pragmas
Inherits: Object
Defined in: lib/sqlite3/database.rb,
ext/sqlite3/database.c

Overview

The Database class encapsulates a single connection to a ::SQLite3 database. Here’s a straightforward example of usage:

require 'sqlite3'

SQLite3::Database.new( "data.db" ) do |db|
  db.execute( "select * from table" ) do |row|
    p row
  end
end

It wraps the lower-level methods provided by the selected driver, and includes the Pragmas module for access to various pragma convenience methods.

The Database class provides type translation services as well, by which the ::SQLite3 data types (which are all represented as strings) may be converted into their corresponding types (as defined in the schemas for their tables). This translation only occurs when querying data from the database–insertions and updates are all still typeless.

Furthermore, the Database class has been designed to work well with the ArrayFields module from Ara Howard. If you require the ArrayFields module before performing a query, and if you have not enabled results as hashes, then the results will all be indexible by field name.

Thread safety

When threadsafe? returns true, it is safe to share instances of the database class among threads without adding specific locking. Other object instances may require applications to provide their own locks if they are to be shared among threads. Please see the README.md for more information.

SQLite Extensions

Database supports the universe of sqlite extensions. It’s possible to load an extension into an existing Database object using the #load_extension method and passing a filesystem path:

db = SQLite3::Database.new(":memory:")
db.enable_load_extension(true)
db.load_extension("/path/to/extension")

As of v2.4.0, it’s also possible to pass an object that responds to #to_path. This documentation will refer to the supported interface as _ExtensionSpecifier, which can be expressed in RBS syntax as:

interface _ExtensionSpecifier
  def to_path: () → String
end

So, for example, if you are using the sqlean gem which provides modules that implement this interface, you can pass the module directly:

db = SQLite3::Database.new(":memory:")
db.enable_load_extension(true)
db.load_extension(SQLean::Crypto)

It’s also possible in v2.4.0+ to load extensions via the Database constructor by using the extensions: keyword argument to pass an array of ::String paths or extension specifiers:

db = SQLite3::Database.new(":memory:", extensions: ["/path/to/extension", SQLean::Crypto])

Note that when loading extensions via the constructor, there is no need to call #enable_load_extension; however it is still necessary to call #enable_load_extensions before any subsequently invocations of #load_extension on the initialized Database object.

You can load extensions in a Rails application by using the extensions: configuration option:

# config/database.yml
development:
  adapter: sqlite3
  extensions:
    - .sqlpkg/nalgeon/crypto/crypto.so # a filesystem path
    - <%= SQLean::UUID.to_path %>      # or ruby code returning a path

Constant Summary

Pragmas - Included

AUTO_VACUUM_MODES, ENCODINGS, JOURNAL_MODES, LOCKING_MODES, SYNCHRONOUS_MODES, TEMP_STORE_MODES, WAL_CHECKPOINTS

Class Method Summary

Instance Attribute Summary

Pragmas - Included

#application_id, #application_id=, #auto_vacuum, #auto_vacuum=, #automatic_index, #automatic_index=, #busy_timeout, #busy_timeout=, #cache_size, #cache_size=, #cache_spill, #cache_spill=, #case_sensitive_like=, #cell_size_check, #cell_size_check=, #checkpoint_fullfsync, #checkpoint_fullfsync=, #count_changes, #count_changes=, #default_cache_size, #default_cache_size=, #default_synchronous, #default_synchronous=, #default_temp_store, #default_temp_store=, #defer_foreign_keys, #defer_foreign_keys=, #encoding, #encoding=, #foreign_keys, #foreign_keys=, #full_column_names, #full_column_names=, #fullfsync, #fullfsync=, #ignore_check_constraints=, #journal_mode, #journal_mode=, #journal_size_limit, #journal_size_limit=, #legacy_file_format, #legacy_file_format=, #locking_mode, #locking_mode=, #max_page_count, #max_page_count=, #mmap_size, #mmap_size=, #page_size, #page_size=, #parser_trace=, #query_only, #query_only=, #read_uncommitted, #read_uncommitted=, #recursive_triggers, #recursive_triggers=, #reverse_unordered_selects, #reverse_unordered_selects=, #schema_cookie, #schema_cookie=, #schema_version, #schema_version=, #secure_delete, #secure_delete=, #short_column_names, #short_column_names=, #soft_heap_limit, #soft_heap_limit=, #synchronous, #synchronous=, #temp_store, #temp_store=, #threads, #threads=, #user_cookie, #user_cookie=, #user_version, #user_version=, #vdbe_addoptrace=, #vdbe_debug=, #vdbe_listing=, #vdbe_trace, #vdbe_trace=, #wal_autocheckpoint, #wal_autocheckpoint=, #wal_checkpoint, #wal_checkpoint=, #writable_schema=

Instance Method Summary

Pragmas - Included

#collation_list

:yields: row.
#compile_options

:yields: row.
#data_version,
#database_list

:yields: row.
#foreign_key_check

:yields: row.
#foreign_key_list

:yields: row.
#freelist_count,
#get_boolean_pragma

Returns true or false depending on the value of the named pragma.
#get_enum_pragma

Return the value of the given pragma.
#get_int_pragma

Returns the value of the given pragma as an integer.
#get_query_pragma

Requests the given pragma (and parameters), and if the block is given, each row of the result set will be yielded to it.
#incremental_vacuum

:yields: row.
#index_info

:yields: row.
#index_list

:yields: row.
#index_xinfo

:yields: row.
#integrity_check

:yields: row.
#optimize

Attempt to optimize the database.
#page_count,
#quick_check

:yields: row.
#set_boolean_pragma

Sets the given pragma to the given boolean value.
#set_enum_pragma

Set the value of the given pragma to mode.
#set_int_pragma

Set the value of the given pragma to the integer value of the value parameter.
#shrink_memory,
#stats

:yields: row.
#table_info

Returns information about table.
#tweak_default

Since SQLite 3.3.8, the table_info pragma has returned the default value of the row as a quoted SQL value.
#version_compare

Compares two version strings.

Constructor Details

.new(file, options = {}) ⇒ Database

Create a new Database object that opens the given file.

Supported permissions options:

  • the default mode is READWRITE | CREATE

  • readonly: boolean (default false), true to set the mode to READONLY

  • readwrite: boolean (default false), true to set the mode to READWRITE

  • flags: set the mode to a combination of Constants::Open flags.

Supported encoding options:

  • utf16: boolish (default false), is the filename’s encoding UTF-16 (only needed if the filename encoding is not UTF_16LE or BE)

Other supported options:

  • strict: boolish (default false), disallow the use of double-quoted string literals (see www.sqlite.org/quirks.html#double_quoted_string_literals_are_accepted)

  • results_as_hash: boolish (default false), return rows as hashes instead of arrays

  • default_transaction_mode: one of :deferred (default), :immediate, or :exclusive. If a mode is not specified in a call to #transaction, this will be the default transaction mode.

  • extensions: Array[String | _ExtensionSpecifier] SQLite extensions to load into the database. See Database@SQLite+Extensions for more information.

[ GitHub ] 

  


# File 'lib/sqlite3/database.rb', line 141



def initialize file, options = {}, zvfs = nil
  mode = Constants::Open::READWRITE | Constants::Open::CREATE

  file = file.to_path if file.respond_to? :to_path
  if file.encoding == ::Encoding::UTF_16LE || file.encoding == ::Encoding::UTF_16BE || options[:utf16]
    open16 file
  else
    # The three primary flag values for sqlite3_open_v2 are:
    # SQLITE_OPEN_READONLY
    # SQLITE_OPEN_READWRITE
    # SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE -- always used for sqlite3_open and sqlite3_open16
    mode = Constants::Open::READONLY if options[:readonly]

    if options[:readwrite]
      raise "conflicting options: readonly and readwrite" if options[:readonly]
      mode = Constants::Open::READWRITE
    end

    if options[:flags]
      if options[:readonly] || options[:readwrite]
        raise "conflicting options: flags with readonly and/or readwrite"
      end
      mode = options[:flags]
    end

    open_v2 file.encode("utf-8"), mode, zvfs

    if options[:strict]
      disable_quirk_mode
    end
  end

  @tracefunc = nil
  @authorizer = nil
  @progress_handler = nil
  @collations = {}
  @functions = {}
  @results_as_hash = options[:results_as_hash]
  @readonly = mode & Constants::Open::READONLY != 0
  @default_transaction_mode = options[:default_transaction_mode] || :deferred

  initialize_extensions(options[:extensions])

  ForkSafety.track(self)

  if block_given?
    begin
      yield self
    ensure
      close
    end
  end
end


  







Class Method Details



  

    .open(*args)  
  



  

    

Without block works exactly as new. With block, like new closes the database at the end, but unlike new returns the result of the block instead of the database instance.


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 95



def open(*args)
  database = new(*args)

  if block_given?
    begin
      yield database
    ensure
      database.close
    end
  else
    database
  end
end


  








  

    .quote(string)  
  



  

    

Quotes the given string, making it safe to use in an SQL statement. It replaces all instances of the single-quote character with two single-quote characters. The modified string is returned.


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 112



def quote(string)
  string.gsub("'", "''")
end


  







Instance Attribute Details



  

    #busy_handler_timeout=(milliseconds)   (writeonly)
  



  

    

Sets a #busy_handler that releases the GVL between retries, but only retries up to the indicated number of milliseconds. This is an alternative to #busy_timeout, which holds the GVL while SQLite sleeps and retries.


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 692



def busy_handler_timeout=(milliseconds)
  timeout_seconds = milliseconds.fdiv(1000)

  busy_handler do |count|
    now = Process.clock_gettime(Process::CLOCK_MONOTONIC)
    if count.zero?
      @timeout_deadline = now + timeout_seconds
    elsif now > @timeout_deadline
      next false
    else
      sleep(0.001)
    end
  end
end


  








  

    #closed?  ⇒ Boolean  (readonly)  



  

    

Returns true if this database instance has been closed (see #close).


  



  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 224



static VALUE
closed_p(VALUE self)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);

    if (!ctx->db) { return Qtrue; }

    return Qfalse;
}


  








  

    #collations   (readonly)
  

  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 87



attr_reader :collations


  








  

    #extended_result_codes=(true)   (writeonly)  



  

    

Enable extended result codes in SQLite.  These result codes allow for more detailed exception reporting, such a which type of constraint is violated.


  



  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 706



static VALUE
set_extended_result_codes(VALUE self, VALUE enable)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    CHECK(ctx->db, sqlite3_extended_result_codes(ctx->db, RTEST(enable) ? 1 : 0));

    return self;
}


  








  

    #readonly?  ⇒ Boolean  (readonly)
  



  

    

Returns true if the database has been open in readonly mode A helper to check before performing any operation


  





  


  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 684



def readonly?
  @readonly
end


  








  

    #results_as_hash   (rw)
  



  

    

A boolean that indicates whether rows in result sets should be returned as hashes or not. By default, rows are returned as arrays.


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 119



attr_accessor :results_as_hash


  








  

    #statement_timeout=(ms)   (writeonly)  



  

    

Indicates that if a query lasts longer than the indicated number of milliseconds, SQLite should interrupt that query and return an error. By default, SQLite does not interrupt queries. To restore the default behavior, send 0 as the ms parameter.


  



  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 363



static VALUE
set_statement_timeout(VALUE self, VALUE milliseconds)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);

    ctx->stmt_timeout = NUM2INT(milliseconds);
    int n = NUM2INT(milliseconds) == 0 ? -1 : 1000;

    sqlite3_progress_handler(ctx->db, n, rb_sqlite3_statement_timeout, (void *)ctx);

    return self;
}


  








  

    #transaction_active?  ⇒ Boolean  (readonly)  



  

    

Returns true if there is a transaction active, and false otherwise.


  



  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 824



static VALUE
transaction_active_p(VALUE self)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    return sqlite3_get_autocommit(ctx->db) ? Qfalse : Qtrue;
}


  







Instance Method Details



  

    #authorizer(&block)  
  



  

    

Installs (or removes) a block that will be invoked for every access to the database. If the block returns 0 (or nil), the statement is allowed to proceed. Returning 1 causes an authorization error to occur, and returning 2 causes the access to be silently denied.


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 206



def authorizer(&block)
  self.authorizer = block
end


  








  

    #set_authorizer=(auth)    



  

    

Set the authorizer for this database.  auth must respond to call, and call must take 5 arguments.



Installs (or removes) a block that will be invoked for every access to the database. If the block returns 0 (or true), the statement is allowed to proceed. Returning 1 or false causes an authorization error to occur, and returning 2 or nil causes the access to be silently denied.


  



  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 659



static VALUE
set_authorizer(VALUE self, VALUE authorizer)
{
    sqlite3RubyPtr ctx;
    int status;

    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    status = sqlite3_set_authorizer(
                 ctx->db, NIL_P(authorizer) ? NULL : rb_sqlite3_auth, (void *)self
             );

    CHECK(ctx->db, status);

    rb_iv_set(self, "@authorizer", authorizer);

    return self;
}


  








  

    #build_result_set(stmt)  
  



  

    

Given a statement, return a result set. This is not intended for general consumption :nodoc:


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 789



def build_result_set stmt
  if results_as_hash
    HashResultSet.new(self, stmt)
  else
    ResultSet.new(self, stmt)
  end
end


  








  

    

      #busy_handler {|count| ... } 
      #busy_handler(Class.new { def call count; end }.new)  
    

  



  

    

Register a busy handler with this database instance. When a requested resource is busy, this handler will be invoked. If the handler returns false, the operation will be aborted; otherwise, the resource will be requested again.



The handler will be invoked with the name of the resource that was busy, and the number of times it has been retried.



See also the mutually exclusive #busy_timeout.


  





  


  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 313



static VALUE
busy_handler(int argc, VALUE *argv, VALUE self)
{
    sqlite3RubyPtr ctx;
    VALUE block;
    int status;

    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    rb_scan_args(argc, argv, "01", &block);

    if (NIL_P(block) && rb_block_given_p()) { block = rb_block_proc(); }
    RB_OBJ_WRITE(self, &ctx->busy_handler, block);

    status = sqlite3_busy_handler(
                 ctx->db,
                 NIL_P(block) ? NULL : rb_sqlite3_busy_handler,
                 (void *)ctx
             );

    CHECK(ctx->db, status);

    return self;
}


  








  

    #busy_timeout(milliseconds)  
  



  

    

Alias for Pragmas#busy_timeout=.


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 386



alias_method :busy_timeout, :busy_timeout=


  








  

    #busy_timeout=(ms)    



  

    

Indicates that if a request for a resource terminates because that resource is busy, SQLite should sleep and retry for up to the indicated number of milliseconds. By default, SQLite does not retry busy resources. To restore the default behavior, send 0 as the ms parameter.



See also the mutually exclusive #busy_handler.


  



  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 689



static VALUE
set_busy_timeout(VALUE self, VALUE timeout)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    CHECK(ctx->db, sqlite3_busy_timeout(ctx->db, (int)NUM2INT(timeout)));

    return self;
}


  








  

    #changes    



  

    

Returns the number of changes made to this database instance by the last operation performed. Note that a “delete from table” without a where clause will not affect this value.


  



  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 614



static VALUE
changes(VALUE self)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    return INT2NUM(sqlite3_changes(ctx->db));
}


  








  

    #close  
  



  

    

Close the database and release all associated resources.



⚠ Writable connections that are carried across a fork() are not completely closed. Sqlite does not support forking, and fully closing a writable connection that has been carried across a fork may corrupt the database. Since it is an incomplete close, not all memory resources are freed, but this is safer than risking data loss.



See adr/2024-09-fork-safety.md for more information on fork safety.


  



  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 193



static VALUE
sqlite3_rb_close(VALUE self)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);

    close_or_discard_db(ctx);

    rb_iv_set(self, "-aggregators", Qnil);

    return self;
}


  








  

    #collation(name, comparator)    



  

    

Add a collation with name name, and a comparator object.  The comparator object should implement a method called “compare” that takes two parameters and returns an integer less than, equal to, or greater than 0.


  



  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 753



static VALUE
collation(VALUE self, VALUE name, VALUE comparator)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    CHECK(ctx->db, sqlite3_create_collation(
              ctx->db,
              StringValuePtr(name),
              SQLITE_UTF8,
              (void *)comparator,
              NIL_P(comparator) ? NULL : rb_comparator_func));

    /* Make sure our comparator doesn't get garbage collected. */
    rb_hash_aset(rb_iv_get(self, "@collations"), name, comparator);

    return self;
}


  








  

    #commit  
  



  

    

Commits the current transaction. If there is no current transaction, this will cause an error to be raised. This returns true, in order to allow it to be used in idioms like abort? and rollback or commit.


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 668



def commit
  execute "commit transaction"
  true
end


  








  

    #complete?(sql)    



  

    

Return true if the string is a valid (ie, parsable) SQL statement, and false otherwise.


  



  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 598



static VALUE
complete_p(VALUE UNUSED(self), VALUE sql)
{
    if (sqlite3_complete(StringValuePtr(sql))) {
        return Qtrue;
    }

    return Qfalse;
}


  








  

    #create_aggregate(name, arity, step = nil, finalize = nil, text_rep = Constants::TextRep::ANY, &block)  
  



  

    

Creates a new aggregate function for use in SQL statements. Aggregate functions are functions that apply over every row in the result set, instead of over just a single row. (A very common aggregate function is the “count” function, for determining the number of rows that match a query.)



The new function will be added as name, with the given arity. (For variable arity functions, use -1 for the arity.)



The step parameter must be a proc object that accepts as its first parameter a Database::FunctionProxy instance (representing the function invocation), with any subsequent parameters (up to the function’s arity). The step callback will be invoked once for each row of the result set.



The finalize parameter must be a proc object that accepts only a single parameter, the Database::FunctionProxy instance representing the current function invocation. It should invoke FunctionProxy#result= to store the result of the function.



Example:



db.create_aggregate( "lengths", 1 ) do
  step do |func, value|
    func[ :total ] ||= 0
    func[ :total ] += ( value ? value.length : 0 )
  end

  finalize do |func|
    func.result = func[ :total ] || 0
  end
end

puts db.get_first_value( "select lengths(name) from table" )



See also #create_aggregate_handler for a more object-oriented approach to aggregate functions.


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 456



def create_aggregate(name, arity, step = nil, finalize = nil,
  text_rep = Constants::TextRep::ANY, &block)

  proxy = Class.new do
    def self.step(&block)
      define_method(:step_with_ctx, &block)
    end

    def self.finalize(&block)
      define_method(:finalize_with_ctx, &block)
    end
  end

  if block
    proxy.instance_eval(&block)
  else
    proxy.class_eval do
      define_method(:step_with_ctx, step)
      define_method(:finalize_with_ctx, finalize)
    end
  end

  proxy.class_eval do
    # class instance variables
    @name = name
    @arity = arity

    def self.name
      @name
    end

    def self.arity
      @arity
    end

    def initialize
      @ctx = FunctionProxy.new
    end

    def step(*args)
      step_with_ctx(@ctx, *args)
    end

    def finalize
      finalize_with_ctx(@ctx)
      @ctx.result
    end
  end
  define_aggregator2(proxy, name)
end


  








  

    #create_aggregate_handler(handler)  
  



  

    

This is another approach to creating an aggregate function (see #create_aggregate). Instead of explicitly specifying the name, callbacks, arity, and type, you specify a factory object (the “handler”) that knows how to obtain all of that information. The handler should respond to the following messages:


arity




corresponds to the arity parameter of #create_aggregate. This message is optional, and if the handler does not respond to it, the function will have an arity of -1.


name




this is the name of the function. The handler must implement this message.


.new




this must be implemented by the handler. It should return a new instance of the object that will handle a specific invocation of the function.





The handler instance (the object returned by the .new message, described above), must respond to the following messages:


step




this is the method that will be called for each step of the aggregate function’s evaluation. It should implement the same signature as the step callback for #create_aggregate.


finalize




this is the method that will be called to finalize the aggregate function’s evaluation. It should implement the same signature as the finalize callback for #create_aggregate.





Example:



class LengthsAggregateHandler
  def self.arity; 1; end
  def self.name; 'lengths'; end

  def initialize
    @total = 0
  end

  def step( ctx, name )
    @total += ( name ? name.length : 0 )
  end

  def finalize( ctx )
    ctx.result = @total
  end
end

db.create_aggregate_handler( LengthsAggregateHandler )
puts db.get_first_value( "select lengths(name) from A" )


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 554



def create_aggregate_handler(handler)
  # This is a compatibility shim so the (basically pointless) FunctionProxy
  # "ctx" object is passed as first argument to both step() and finalize().
  # Now its up to the library user whether he prefers to store his
  # temporaries as instance variables or fields in the FunctionProxy.
  # The library user still must set the result value with
  # FunctionProxy.result= as there is no backwards compatible way to
  # change this.
  proxy = Class.new(handler) do
    def initialize
      super
      @fp = FunctionProxy.new
    end

    def step(*args)
      super(@fp, *args)
    end

    def finalize
      super(@fp)
      @fp.result
    end
  end
  define_aggregator2(proxy, proxy.name)
  self
end


  








  

    #create_function(name, arity, text_rep = Constants::TextRep::UTF8, &block)  
  



  

    

Creates a new function for use in SQL statements. It will be added as name, with the given arity. (For variable arity functions, use -1 for the arity.)



The block should accept at least one parameter–the Database::FunctionProxy instance that wraps this function invocation–and any other arguments it needs (up to its arity).



The block does not return a value directly. Instead, it will invoke the FunctionProxy#result= method on the func parameter and indicate the return value that way.



Example:



db.create_function( "maim", 1 ) do |func, value|
  if value.nil?
    func.result = nil
  else
    func.result = value.split(//).sort.join
  end
end

puts db.get_first_value( "select maim(name) from table" )


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 411



def create_function name, arity, text_rep = Constants::TextRep::UTF8, &block
  define_function_with_flags(name, text_rep) do |*args|
    fp = FunctionProxy.new
    block.call(fp, *args)
    fp.result
  end
  self
end


  








  

    #db_filename(database_name)   (private)  



  

    

Returns the file associated with database_name.  Can return nil or an empty string if the database is temporary, or in-memory.


  



  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 912



static VALUE
db_filename(VALUE self, VALUE db_name)
{
    sqlite3RubyPtr ctx;
    const char *fname;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    fname = sqlite3_db_filename(ctx->db, StringValueCStr(db_name));

    if (fname) { return SQLITE3_UTF8_STR_NEW2(fname); }
    return Qnil;
}


  








  

    #define_aggregator(name, aggregator)  
  



  

    

Define an aggregate function named name using a object template object aggregator. aggregator must respond to step and finalize. step will be called with row information and finalize must return the return value for the aggregator function.



_API Change:_ aggregator must also implement clone. The provided aggregator object will serve as template that is cloned to provide the individual instances of the aggregate function. Regular ruby objects already provide a suitable clone. The functions arity is the arity of the step method.


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 591



def define_aggregator(name, aggregator)
  # Previously, this has been implemented in C. Now this is just yet
  # another compatibility shim
  proxy = Class.new do
    @template = aggregator
    @name = name

    def self.template
      @template
    end

    def self.name
      @name
    end

    def self.arity
      # this is what sqlite3_obj_method_arity did before
      @template.method(:step).arity
    end

    def initialize
      @klass = self.class.template.clone
    end

    def step(*args)
      @klass.step(*args)
    end

    def finalize
      @klass.finalize
    end
  end
  define_aggregator2(proxy, name)
  self
end


  








  

    #define_aggregator2   (private)
  

  [ GitHub ]






  

    #define_function(name) {|args, ...| ... }   



  

    

Define a function named name with args.  The arity of the block will be used as the arity for the function defined.


  



  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 541



static VALUE
define_function(VALUE self, VALUE name)
{
    return define_function_with_flags(self, name, INT2FIX(SQLITE_UTF8));
}


  








  

    #define_function_with_flags(name, flags) {|args, ...| ... }   



  

    

Define a function named name with args using TextRep bitflags flags.  The arity of the block will be used as the arity for the function defined.


  



  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 506



static VALUE
define_function_with_flags(VALUE self, VALUE name, VALUE flags)
{
    sqlite3RubyPtr ctx;
    VALUE block;
    int status;

    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    block = rb_block_proc();

    status = sqlite3_create_function(
                 ctx->db,
                 StringValuePtr(name),
                 rb_proc_arity(block),
                 NUM2INT(flags),
                 (void *)block,
                 rb_sqlite3_func,
                 NULL,
                 NULL
             );

    CHECK(ctx->db, status);

    rb_hash_aset(rb_iv_get(self, "@functions"), name, block);

    return self;
}


  








  

    #disable_quirk_mode   (private)
  

  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 164



static VALUE
rb_sqlite3_disable_quirk_mode(VALUE self)
{
#if defined SQLITE_DBCONFIG_DQS_DDL
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);

    if (!ctx->db) { return Qfalse; }

    sqlite3_db_config(ctx->db, SQLITE_DBCONFIG_DQS_DDL, 0, (void *)0);
    sqlite3_db_config(ctx->db, SQLITE_DBCONFIG_DQS_DML, 0, (void *)0);

    return Qtrue;
#else
    return Qfalse;
#endif
}


  








  

    #discard   (private)
  



  

    

private method, primarily for testing


  



  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 207



static VALUE
sqlite3_rb_discard(VALUE self)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);

    discard_db(ctx);

    rb_iv_set(self, "-aggregators", Qnil);

    return self;
}


  








  

    #enable_load_extension(onoff)    



  

    

Enable or disable extension loading.


  



  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 797



static VALUE
enable_load_extension(VALUE self, VALUE onoff)
{
    sqlite3RubyPtr ctx;
    int onoffparam;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    if (Qtrue == onoff) {
        onoffparam = 1;
    } else if (Qfalse == onoff) {
        onoffparam = 0;
    } else {
        onoffparam = (int)NUM2INT(onoff);
    }

    CHECK(ctx->db, sqlite3_enable_load_extension(ctx->db, onoffparam));

    return self;
}


  








  

    #encoding    



  

    

Fetch the encoding set on this database


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 198



def encoding
  prepare("PRAGMA encoding") { |stmt| Encoding.find(stmt.first.first) }
end


  








  

    #errcode    



  

    

Return an integer representing the last error to have occurred with this database.


  



  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 583



static VALUE
errcode_(VALUE self)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    return INT2NUM(sqlite3_errcode(ctx->db));
}


  








  

    #errmsg    



  

    

Return a string describing the last error to have occurred with this database.


  



  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 568



static VALUE
errmsg(VALUE self)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    return rb_str_new2(sqlite3_errmsg(ctx->db));
}


  








  

    #exec_batch(sql, results_as_hash)   (private)
  



  

    

Is invoked by calling db.execute_batch2(sql, &block)



Executes all statements in a given string separated by semicolons. If a query is made, all values returned are strings (except for ‘NULL’ values which return nil), so the user may parse values with a block. If no query is made, an empty array will be returned.


  



  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 881



static VALUE
exec_batch(VALUE self, VALUE sql, VALUE results_as_hash)
{
    sqlite3RubyPtr ctx;
    int status;
    VALUE callback_ary = rb_ary_new();
    char *errMsg;

    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    if (results_as_hash == Qtrue) {
        status = sqlite3_exec(ctx->db, StringValuePtr(sql), (sqlite3_callback)hash_callback_function,
                              (void *)callback_ary,
                              &errMsg);
    } else {
        status = sqlite3_exec(ctx->db, StringValuePtr(sql), (sqlite3_callback)regular_callback_function,
                              (void *)callback_ary,
                              &errMsg);
    }

    CHECK_MSG(ctx->db, status, errMsg);

    return callback_ary;
}


  








  

    #execute(sql, bind_vars = [], &block)  
  



  

    

Executes the given SQL statement. If additional parameters are given, they are treated as bind variables, and are bound to the placeholders in the query.



Note that if any of the values passed to this are hashes, then the key/value pairs are each bound separately, with the key being used as the name of the placeholder to bind the value to.



The block is optional. If given, it will be invoked for each row returned by the query. Otherwise, any results are accumulated into an array and returned wholesale.



See also #execute2, #query, and #execute_batch for additional ways of executing statements.


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 247



def execute sql, bind_vars = [], &block
  prepare(sql) do |stmt|
    stmt.bind_params(bind_vars)
    stmt = build_result_set stmt

    if block
      stmt.each do |row|
        yield row
      end
    else
      stmt.to_a.freeze
    end
  end
end


  








  

    #execute2(sql, *bind_vars)  
  



  

    

Executes the given SQL statement, exactly as with #execute. However, the first row returned (either via the block, or in the returned array) is always the names of the columns. Subsequent rows correspond to the data from the result set.



Thus, even if the query itself returns no rows, this method will always return at least one row–the names of the columns.



See also #execute, #query, and #execute_batch for additional ways of executing statements.


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 272



def execute2(sql, *bind_vars)
  prepare(sql) do |stmt|
    result = stmt.execute(*bind_vars)
    if block_given?
      yield stmt.columns
      result.each { |row| yield row }
    else
      return result.each_with_object([stmt.columns]) { |row, arr|
               arr << row
             }
    end
  end
end


  








  

    #execute_batch(sql, bind_vars = [])  
  



  

    

Executes all SQL statements in the given string. By contrast, the other means of executing queries will only execute the first statement in the string, ignoring all subsequent statements. This will execute each one in turn. The same bind parameters, if given, will be applied to each statement.



This always returns the result of the last statement.



See also #execute_batch2 for additional ways of executing statements.


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 296



def execute_batch(sql, bind_vars = [])
  sql = sql.strip
  result = nil
  until sql.empty?
    prepare(sql) do |stmt|
      unless stmt.closed?
        # FIXME: this should probably use sqlite3's api for batch execution
        # This implementation requires stepping over the results.
        if bind_vars.length == stmt.bind_parameter_count
          stmt.bind_params(bind_vars)
        end
        result = stmt.step
      end
      sql = stmt.remainder.strip
    end
  end

  result
end


  








  

    #execute_batch2(sql, &block)  
  



  

    

Executes all SQL statements in the given string. By contrast, the other means of executing queries will only execute the first statement in the string, ignoring all subsequent statements. This will execute each one in turn. Bind parameters cannot be passed to #execute_batch2.



If a query is made, all values will be returned as strings. If no query is made, an empty array will be returned.



Because all values except for ‘NULL’ are returned as strings, a block can be passed to parse the values accordingly.



See also #execute_batch for additional ways of executing statements.


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 329



def execute_batch2(sql, &block)
  if block
    result = exec_batch(sql, @results_as_hash)
    result.map do |val|
      yield val
    end
  else
    exec_batch(sql, @results_as_hash)
  end
end


  








  

    #filename(db_name = "main")  
  



  

    

Returns the filename for the database named db_name.  db_name defaults to “main”.  Main return nil or an empty string if the database is temporary or in-memory.


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 229



def filename db_name = "main"
  db_filename db_name
end


  








  

    #get_first_row(sql, *bind_vars)  
  



  

    

A convenience method for obtaining the first row of a result set, and discarding all others. It is otherwise identical to #execute.



See also #get_first_value.


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 368



def get_first_row(sql, *bind_vars)
  execute(sql, *bind_vars).first
end


  








  

    #get_first_value(sql, *bind_vars)  
  



  

    

A convenience method for obtaining the first value of the first row of a result set, and discarding all other values and rows. It is otherwise identical to #execute.



See also #get_first_row.


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 377



def get_first_value(sql, *bind_vars)
  query(sql, bind_vars) do |rs|
    if (row = rs.next)
      return @results_as_hash ? row[rs.columns[0]] : row[0]
    end
  end
  nil
end


  








  

    #initialize_extensions(extensions)  
  

  

    This method is for internal use only.
  



  

    
  





  
Raises:


    
  
  • 
    (TypeError)
  
    • 





  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 737



def initialize_extensions(extensions) # :nodoc:
  return if extensions.nil?
  raise TypeError, "extensions must be an Array" unless extensions.is_a?(Array)
  return if extensions.empty?

  begin
    enable_load_extension(true)

    extensions.each do |extension|
      load_extension(extension)
    end
  ensure
    enable_load_extension(false)
  end
end


  








  

    #interrupt    



  

    

Interrupts the currently executing operation, causing it to abort.


  



  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 551



static VALUE
interrupt(VALUE self)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    sqlite3_interrupt(ctx->db);

    return self;
}


  








  

    #last_insert_row_id    



  

    

Obtains the unique row ID of the last row to be inserted by this Database instance.


  



  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 382



static VALUE
last_insert_row_id(VALUE self)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    return LL2NUM(sqlite3_last_insert_rowid(ctx->db));
}


  








  

    #load_extension(extension_specifier)  ⇒ self   



  

    

Loads an SQLite extension library from the named file. Extension loading must be enabled using #enable_load_extension prior to using this method.



See also: Database@SQLite+Extensions


Parameters




  • 

    extension_specifier: (String | _ExtensionSpecifier) If a ::String, it is the filesystem path to the sqlite extension file. If an object that responds to #to_path, the return value of that method is used as the filesystem path to the sqlite extension file.
    



Example




Using a filesystem path:





db.load_extension("/path/to/my_extension.so")


Example




Using the sqlean gem:





db.load_extension(SQLean::VSV)


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 728



def load_extension(extension_specifier)
  if extension_specifier.respond_to?(:to_path)
    extension_specifier = extension_specifier.to_path
  elsif !extension_specifier.is_a?(String)
    raise TypeError, "extension_specifier #{extension_specifier.inspect} is not a String or a valid extension specifier object"
  end
  load_extension_internal(extension_specifier)
end


  








  

    #load_extension_internal(file)   (private)
  

  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 774



static VALUE
load_extension_internal(VALUE self, VALUE file)
{
    sqlite3RubyPtr ctx;
    int status;
    char *errMsg;

    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    status = sqlite3_load_extension(ctx->db, StringValuePtr(file), 0, &errMsg);

    CHECK_MSG(ctx->db, status, errMsg);

    return self;
}


  








  

    #open16(file)   (private)
  

  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 926



static VALUE
rb_sqlite3_open16(VALUE self, VALUE file)
{
    int status;
    sqlite3RubyPtr ctx;

    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);

#if defined TAINTING_SUPPORT
#if defined StringValueCStr
    StringValuePtr(file);
    rb_check_safe_obj(file);
#else
    Check_SafeStr(file);
#endif
#endif

    // sqlite3_open16 implicitly uses flags (SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE)
    // see https://www.sqlite.org/capi3ref.html#sqlite3_open
    // so we do not ever set SQLITE3_RB_DATABASE_READONLY in ctx->flags
    status = sqlite3_open16(utf16_string_value_ptr(file), &ctx->db);

    CHECK(ctx->db, status)

    return INT2NUM(status);
}


  








  

    #open_v2(file, mode, zvfs)   (private)
  

  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 130



static VALUE
rb_sqlite3_open_v2(VALUE self, VALUE file, VALUE mode, VALUE zvfs)
{
    sqlite3RubyPtr ctx;
    int status;
    int flags;

    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);

#if defined TAINTING_SUPPORT
#  if defined StringValueCStr
    StringValuePtr(file);
    rb_check_safe_obj(file);
#  else
    Check_SafeStr(file);
#  endif
#endif

    flags = NUM2INT(mode);
    status = sqlite3_open_v2(
                 StringValuePtr(file),
                 &ctx->db,
                 flags,
                 NIL_P(zvfs) ? NULL : StringValuePtr(zvfs)
             );

    CHECK(ctx->db, status);
    if (flags & SQLITE_OPEN_READONLY) {
        ctx->flags |= SQLITE3_RB_DATABASE_READONLY;
    }

    return self;
}


  








  

    #prepare(sql)  
  



  

    

Returns a Statement object representing the given SQL. This does not execute the statement; it merely prepares the statement for execution.



The Statement can then be executed using Statement#execute.


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 215



def prepare sql
  stmt = SQLite3::Statement.new(self, sql)
  return stmt unless block_given?

  begin
    yield stmt
  ensure
    stmt.close unless stmt.closed?
  end
end


  








  

    #query(sql, bind_vars = [])  
  



  

    

This is a convenience method for creating a statement, binding parameters to it, and calling execute:



result = db.query( "select * from foo where a=?", [5])
# is the same as
result = db.prepare( "select * from foo where a=?" ).execute( 5 )



You must be sure to call #close on the ResultSet instance that is returned, or you could have problems with locks on the table. If called with a block, #close will be invoked implicitly when the block terminates.


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 351



def query(sql, bind_vars = [])
  result = prepare(sql).execute(bind_vars)
  if block_given?
    begin
      yield result
    ensure
      result.close
    end
  else
    result
  end
end


  








  

    #rollback  
  



  

    

Rolls the current transaction back. If there is no current transaction, this will cause an error to be raised. This returns true, in order to allow it to be used in idioms like abort? and rollback or commit.


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 677



def rollback
  execute "rollback transaction"
  true
end


  








  

    #total_changes  ⇒ ?   



  

    

Returns the total number of changes made to this database instance since it was opened.


  



  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 240



static VALUE
total_changes(VALUE self)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    return INT2NUM(sqlite3_total_changes(ctx->db));
}


  








  

    

      #trace {|sql| ... } 
      #trace(Class.new { def call sql; end }.new)  
    

  



  

    

Installs (or removes) a block that will be invoked for every SQL statement executed. The block receives one parameter: the SQL statement executed. If the block is nil, any existing tracer will be uninstalled.


  





  


  [ GitHub ]


  

  


# File 'ext/sqlite3/database.c', line 266



static VALUE
trace(int argc, VALUE *argv, VALUE self)
{
    sqlite3RubyPtr ctx;
    VALUE block;

    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    rb_scan_args(argc, argv, "01", &block);

    if (NIL_P(block) && rb_block_given_p()) { block = rb_block_proc(); }

    rb_iv_set(self, "@tracefunc", block);

    sqlite3_trace(ctx->db, NIL_P(block) ? NULL : tracefunc, (void *)self);

    return self;
}


  








  

    #transaction(mode = nil)  
  



  

    

Begins a new transaction. Note that nested transactions are not allowed by SQLite, so attempting to nest a transaction will result in a runtime exception.



The mode parameter may be either :deferred, :immediate, or :exclusive. If nil is specified, the default transaction mode, which was passed to #initialize, is used.



If a block is given, the database instance is yielded to it, and the transaction is committed when the block terminates. If the block raises an exception, a rollback will be performed instead. Note that if a block is given, #commit and #rollback should never be called explicitly or you’ll get an error when the block terminates.



If a block is not given, it is the caller’s responsibility to end the transaction explicitly, either by calling #commit, or by calling #rollback.


  



  [ GitHub ]


  

  


# File 'lib/sqlite3/database.rb', line 645



def transaction(mode = nil)
  mode = @default_transaction_mode if mode.nil?
  execute "begin #{mode} transaction"

  if block_given?
    abort = false
    begin
      yield self
    rescue
      abort = true
      raise
    ensure
      abort and rollback or commit
    end
  else
    true
  end
end