Methods

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
ER_FILSORT_ABORT = 1028
 

See dev.mysql.com/doc/refman/5.7/en/error-messages-server.html
ER_FK_INCOMPATIBLE_COLUMNS = 3780
ER_LOCK_DEADLOCK = 1213
ER_LOCK_WAIT_TIMEOUT = 1205
ER_NOT_NULL_VIOLATION = 1048
ER_NO_REFERENCED_ROW = 1216
ER_NO_REFERENCED_ROW_2 = 1452
ER_OUT_OF_RANGE = 1264
ER_QUERY_INTERRUPTED = 1317
ER_QUERY_TIMEOUT = 3024
ER_ROW_IS_REFERENCED = 1217
ER_ROW_IS_REFERENCED_2 = 1451
NATIVE_DATABASE_TYPES = { primary_key: "bigint auto_increment PRIMARY KEY", string: { name: "varchar", limit: 255 }, text: { name: "text" }, 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" }, blob: { name: "blob" }, 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
📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 27
      class_attribute :emulate_booleans, default: true
🔎 See on GitHub

new(connection, logger, connection_options, config)

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 53
      def initialize(connection, logger, connection_options, config)
        super(connection, logger, config)
      end
🔎 See on GitHub

Instance Public methods

begin_db_transaction()

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 213
      def begin_db_transaction
        execute "BEGIN"
      end
🔎 See on GitHub

begin_isolated_db_transaction(isolation)

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 217
      def begin_isolated_db_transaction(isolation)
        execute "SET TRANSACTION ISOLATION LEVEL #{transaction_isolation_levels.fetch(isolation)}"
        begin_db_transaction
      end
🔎 See on GitHub

charset()

Returns the database character set.

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 277
      def charset
        show_variable "character_set_database"
      end
🔎 See on GitHub

collation()

Returns the database collation strategy.

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 282
      def collation
        show_variable "collation_database"
      end
🔎 See on GitHub

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
📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 252
      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 row_format_dynamic_by_default?
          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
🔎 See on GitHub

current_database()

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 272
      def current_database
        query_value("SELECT database()", "SCHEMA")
      end
🔎 See on GitHub

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.

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 327
      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
🔎 See on GitHub

empty_insert_statement_value(primary_key = nil)

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 230
      def empty_insert_statement_value(primary_key = nil)
        "VALUES ()"
      end
🔎 See on GitHub

execute(sql, name = nil)

Executes the SQL statement in the context of this connection.

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 196
      def execute(sql, name = nil)
        materialize_transactions

        log(sql, name) do
          ActiveSupport::Dependencies.interlock.permit_concurrent_loads do
            @connection.query(sql)
          end
        end
      end
🔎 See on GitHub

explain(arel, binds = [])

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 186
      def explain(arel, binds = [])
        sql     = "EXPLAIN #{to_sql(arel, binds)}"
        start   = Concurrent.monotonic_time
        result  = exec_query(sql, "EXPLAIN", binds)
        elapsed = Concurrent.monotonic_time - start

        MySQL::ExplainPrettyPrinter.new.pp(result, elapsed)
      end
🔎 See on GitHub

foreign_keys(table_name)

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 379
      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
🔎 See on GitHub

index_algorithms()

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 144
      def index_algorithms
        { default: +"ALGORITHM = DEFAULT", copy: +"ALGORITHM = COPY", inplace: +"ALGORITHM = INPLACE" }
      end
🔎 See on GitHub

native_database_types()

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 140
      def native_database_types
        NATIVE_DATABASE_TYPES
      end
🔎 See on GitHub

recreate_database(name, options = {})

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

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 238
      def recreate_database(name, options = {})
        drop_database(name)
        sql = create_database(name, options)
        reconnect!
        sql
      end
🔎 See on GitHub

rename_index(table_name, old_name, new_name)

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 331
      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
🔎 See on GitHub

rename_table(table_name, new_name)

Renames a table.

Example:

rename_table('octopuses', 'octopi')
📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 307
      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
🔎 See on GitHub

show_variable(name)

SHOW VARIABLES LIKE 'name'

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 438
      def show_variable(name)
        query_value("SELECT @@#{name}", "SCHEMA")
      rescue ActiveRecord::StatementInvalid
        nil
      end
🔎 See on GitHub

strict_mode?()

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 504
      def strict_mode?
        self.class.type_cast_config_to_boolean(@config.fetch(:strict, true))
      end
🔎 See on GitHub

supports_advisory_locks?()

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 120
      def supports_advisory_locks?
        true
      end
🔎 See on GitHub

supports_bulk_alter?()

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 67
      def supports_bulk_alter?
        true
      end
🔎 See on GitHub

supports_common_table_expressions?()

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 112
      def supports_common_table_expressions?
        if mariadb?
          database_version >= "10.2.1"
        else
          database_version >= "8.0.1"
        end
      end
🔎 See on GitHub

supports_datetime_with_precision?()

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 99
      def supports_datetime_with_precision?
        mariadb? || database_version >= "5.6.4"
      end
🔎 See on GitHub

supports_explain?()

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 83
      def supports_explain?
        true
      end
🔎 See on GitHub

supports_expression_index?()

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 75
      def supports_expression_index?
        !mariadb? && database_version >= "8.0.13"
      end
🔎 See on GitHub

supports_foreign_keys?()

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 91
      def supports_foreign_keys?
        true
      end
🔎 See on GitHub

supports_index_sort_order?()

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 71
      def supports_index_sort_order?
        !mariadb? && database_version >= "8.0.1"
      end
🔎 See on GitHub

supports_indexes_in_create?()

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 87
      def supports_indexes_in_create?
        true
      end
🔎 See on GitHub

supports_insert_on_duplicate_skip?()

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 124
      def supports_insert_on_duplicate_skip?
        true
      end
🔎 See on GitHub

supports_insert_on_duplicate_update?()

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 128
      def supports_insert_on_duplicate_update?
        true
      end
🔎 See on GitHub

supports_optimizer_hints?()

See dev.mysql.com/doc/refman/8.0/en/optimizer-hints.html for more details.

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 108
      def supports_optimizer_hints?
        !mariadb? && database_version >= "5.7.7"
      end
🔎 See on GitHub

supports_transaction_isolation?()

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 79
      def supports_transaction_isolation?
        true
      end
🔎 See on GitHub

supports_views?()

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 95
      def supports_views?
        true
      end
🔎 See on GitHub

supports_virtual_columns?()

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 103
      def supports_virtual_columns?
        mariadb? || database_version >= "5.7.5"
      end
🔎 See on GitHub