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Constants
ER_CANNOT_ADD_FOREIGN = 1215
 
ER_CANNOT_CREATE_TABLE = 1005
 
ER_DATA_TOO_LONG = 1406
 
ER_DO_NOT_HAVE_DEFAULT = 1364
 
ER_DUP_ENTRY = 1062
 

See dev.mysql.com/doc/refman/5.7/en/error-messages-server.html

ER_LOCK_DEADLOCK = 1213
 
ER_LOCK_WAIT_TIMEOUT = 1205
 
ER_NOT_NULL_VIOLATION = 1048
 
ER_NO_REFERENCED_ROW_2 = 1452
 
ER_OUT_OF_RANGE = 1264
 
ER_QUERY_INTERRUPTED = 1317
 
ER_QUERY_TIMEOUT = 3024
 
ER_ROW_IS_REFERENCED_2 = 1451
 
NATIVE_DATABASE_TYPES = { primary_key: "bigint auto_increment PRIMARY KEY", string: { name: "varchar", limit: 255 }, text: { name: "text", limit: 65535 }, integer: { name: "int", limit: 4 }, float: { name: "float", limit: 24 }, decimal: { name: "decimal" }, datetime: { name: "datetime" }, timestamp: { name: "timestamp" }, time: { name: "time" }, date: { name: "date" }, binary: { name: "blob", limit: 65535 }, boolean: { name: "tinyint", limit: 1 }, json: { name: "json" }, }
 
Class Public methods
emulate_booleans

By default, the Mysql2Adapter will consider all columns of type tinyint(1) as boolean. If you wish to disable this emulation you can add the following line to your application.rb file:

ActiveRecord::ConnectionAdapters::Mysql2Adapter.emulate_booleans = false
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 27
class_attribute :emulate_booleans, default: true
new(connection, logger, connection_options, config)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 53
def initialize(connection, logger, connection_options, config)
  super(connection, logger, config)

  @statements = StatementPool.new(self.class.type_cast_config_to_integer(config[:statement_limit]))

  if version < "5.5.8"
    raise "Your version of MySQL (#{version_string}) is too old. Active Record supports MySQL >= 5.5.8."
  end
end
Instance Public methods
begin_db_transaction()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 209
def begin_db_transaction
  execute "BEGIN"
end
begin_isolated_db_transaction(isolation)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 213
def begin_isolated_db_transaction(isolation)
  execute "SET TRANSACTION ISOLATION LEVEL #{transaction_isolation_levels.fetch(isolation)}"
  begin_db_transaction
end
charset()

Returns the database character set.

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 285
def charset
  show_variable "character_set_database"
end
clear_cache!()

Clears the prepared statements cache.

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 173
def clear_cache!
  reload_type_map
  @statements.clear
end
collation()

Returns the database collation strategy.

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 290
def collation
  show_variable "collation_database"
end
create_database(name, options = {})

Create a new MySQL database with optional :charset and :collation. Charset defaults to utf8mb4.

Example:

create_database 'charset_test', charset: 'latin1', collation: 'latin1_bin'
create_database 'matt_development'
create_database 'matt_development', charset: :big5
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 260
def create_database(name, options = {})
  if options[:collation]
    execute "CREATE DATABASE #{quote_table_name(name)} DEFAULT COLLATE #{quote_table_name(options[:collation])}"
  elsif options[:charset]
    execute "CREATE DATABASE #{quote_table_name(name)} DEFAULT CHARACTER SET #{quote_table_name(options[:charset])}"
  elsif supports_longer_index_key_prefix?
    execute "CREATE DATABASE #{quote_table_name(name)} DEFAULT CHARACTER SET `utf8mb4`"
  else
    raise "Configure a supported :charset and ensure innodb_large_prefix is enabled to support indexes on varchar(255) string columns."
  end
end
current_database()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 280
def current_database
  query_value("SELECT database()", "SCHEMA")
end
drop_table(table_name, options = {})

Drops a table from the database.

:force

Set to :cascade to drop dependent objects as well. Defaults to false.

:if_exists

Set to true to only drop the table if it exists. Defaults to false.

:temporary

Set to true to drop temporary table. Defaults to false.

Although this command ignores most options and the block if one is given, it can be helpful to provide these in a migration's change method so it can be reverted. In that case, options and the block will be used by create_table.

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 353
def drop_table(table_name, options = {})
  execute "DROP#{' TEMPORARY' if options[:temporary]} TABLE#{' IF EXISTS' if options[:if_exists]} #{quote_table_name(table_name)}#{' CASCADE' if options[:force] == :cascade}"
end
empty_insert_statement_value(primary_key = nil)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 238
def empty_insert_statement_value(primary_key = nil)
  "VALUES ()"
end
execute(sql, name = nil)

Executes the SQL statement in the context of this connection.

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 192
def execute(sql, name = nil)
  materialize_transactions

  log(sql, name) do
    ActiveSupport::Dependencies.interlock.permit_concurrent_loads do
      @connection.query(sql)
    end
  end
end
explain(arel, binds = [])
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 182
def explain(arel, binds = [])
  sql     = "EXPLAIN #{to_sql(arel, binds)}"
  start   = Time.now
  result  = exec_query(sql, "EXPLAIN", binds)
  elapsed = Time.now - start

  MySQL::ExplainPrettyPrinter.new.pp(result, elapsed)
end
foreign_keys(table_name)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 404
      def foreign_keys(table_name)
        raise ArgumentError unless table_name.present?

        scope = quoted_scope(table_name)

        fk_info = exec_query(<<~SQL, "SCHEMA")
          SELECT fk.referenced_table_name AS 'to_table',
                 fk.referenced_column_name AS 'primary_key',
                 fk.column_name AS 'column',
                 fk.constraint_name AS 'name',
                 rc.update_rule AS 'on_update',
                 rc.delete_rule AS 'on_delete'
          FROM information_schema.referential_constraints rc
          JOIN information_schema.key_column_usage fk
          USING (constraint_schema, constraint_name)
          WHERE fk.referenced_column_name IS NOT NULL
            AND fk.table_schema = #{scope[:schema]}
            AND fk.table_name = #{scope[:name]}
            AND rc.constraint_schema = #{scope[:schema]}
            AND rc.table_name = #{scope[:name]}
        SQL

        fk_info.map do |row|
          options = {
            column: row["column"],
            name: row["name"],
            primary_key: row["primary_key"]
          }

          options[:on_update] = extract_foreign_key_action(row["on_update"])
          options[:on_delete] = extract_foreign_key_action(row["on_delete"])

          ForeignKeyDefinition.new(table_name, row["to_table"], options)
        end
      end
index_algorithms()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 139
def index_algorithms
  { default: +"ALGORITHM = DEFAULT", copy: +"ALGORITHM = COPY", inplace: +"ALGORITHM = INPLACE" }
end
insert_fixtures_set(fixture_set, tables_to_delete = [])
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 543
def insert_fixtures_set(fixture_set, tables_to_delete = [])
  with_multi_statements do
    super { discard_remaining_results }
  end
end
native_database_types()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 135
def native_database_types
  NATIVE_DATABASE_TYPES
end
recreate_database(name, options = {})

Drops the database specified on the name attribute and creates it again using the provided options.

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 246
def recreate_database(name, options = {})
  drop_database(name)
  sql = create_database(name, options)
  reconnect!
  sql
end
rename_index(table_name, old_name, new_name)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 357
def rename_index(table_name, old_name, new_name)
  if supports_rename_index?
    validate_index_length!(table_name, new_name)

    execute "ALTER TABLE #{quote_table_name(table_name)} RENAME INDEX #{quote_table_name(old_name)} TO #{quote_table_name(new_name)}"
  else
    super
  end
end
rename_table(table_name, new_name)

Renames a table.

Example:

rename_table('octopuses', 'octopi')
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 333
def rename_table(table_name, new_name)
  execute "RENAME TABLE #{quote_table_name(table_name)} TO #{quote_table_name(new_name)}"
  rename_table_indexes(table_name, new_name)
end
show_variable(name)

SHOW VARIABLES LIKE 'name'

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 486
def show_variable(name)
  query_value("SELECT @@#{name}", "SCHEMA")
rescue ActiveRecord::StatementInvalid
  nil
end
strict_mode?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 535
def strict_mode?
  self.class.type_cast_config_to_boolean(@config.fetch(:strict, true))
end
supports_advisory_locks?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 115
def supports_advisory_locks?
  true
end
supports_datetime_with_precision?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 99
def supports_datetime_with_precision?
  if mariadb?
    version >= "5.3.0"
  else
    version >= "5.6.4"
  end
end
supports_explain?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 83
def supports_explain?
  true
end
supports_foreign_keys?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 91
def supports_foreign_keys?
  true
end
supports_index_sort_order?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 75
def supports_index_sort_order?
  !mariadb? && version >= "8.0.1"
end
supports_indexes_in_create?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 87
def supports_indexes_in_create?
  true
end
supports_longer_index_key_prefix?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 119
def supports_longer_index_key_prefix?
  if mariadb?
    version >= "10.2.2"
  else
    version >= "5.7.9"
  end
end
supports_transaction_isolation?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 79
def supports_transaction_isolation?
  true
end
supports_views?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 95
def supports_views?
  true
end
supports_virtual_columns?()
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 107
def supports_virtual_columns?
  if mariadb?
    version >= "5.2.0"
  else
    version >= "5.7.5"
  end
end
truncate(table_name, name = nil)
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 294
def truncate(table_name, name = nil)
  execute "TRUNCATE TABLE #{quote_table_name(table_name)}", name
end