MySQL-compatible Description

The MySQL compatibility of MogDB is mainly realized through the Dolphin and kernel. The description of the Dolphin can be found in Dolphin Extension. The MySQL compatibility features implemented in MogDB are shown in the following table.

Table 1 MySQL-compatible features implemented in the MogDB

Category	Overview	Link
DDL	The CREATE DATABASE supports the IF NOT EXISTS option.	CREATE DATABASE
DDL	The CREATE SCHEMA supports the IF NOT EXISTS option.	CREATE SCHEMA
DDL	The ALTER USER supports the IF EXISTS option.	ALTER USER
DDL	ALTER VIEW supports the DEFINER option.	ALTER VIEW
DDL	CREATE VIEW supports the DEFINER option.	CREATE VIEW
DDL	The COMMENT option can be specified in the statements for creating and modifying objects.	ALTER FUNCTION、 ALTER PROCEDURE、 ALTER TABLE、 CREATE FUNCTION、 CREATE INDEX、 CREATE PROCEDURE、 CREATE TABLE、 CREATE TABLE PARTITION、 CREATE TABLE SUBPARTITION
DDL	CREATE TABLE supports the creation of primary keys, UNIQUE indexes, and foreign key constraints.	CREATE TABLE
DDL	ALTER TABLE supports the creation of primary keys, UNIQUE indexes, and foreign key constraints.	ALTER TABLE
DDL	CREATE TABLE supports the creation of auto-increment columns.	CREATE TABLE
DML	DELETE supports the deletion of data from multiple tables.	DELETE
DML	DELETE supports ORDER BY.	DELETE
DML	DELETE supports the deletion of data from a specified partition or subpartition.	DELETE
DML	UPDATE supports the update of data from multiple tables.	UPDATE
DML	UPDATE supports ORDER BY and LIMIT.	UPDATE
DCL	User-defined variables can be set in sessions.	SET
DCL	Global variables of SET can be enhanced.	SET
Data type	The NVARCHAR type is supported.	Character Types
Data type	The SET type is supported.	SET Type
Function and operator	The secure equality operator <=> is supported.	Simple Expressions
Function and operator	The group_concat function is supported.	Aggregate Functions
Function and operator	The security functions aes_decrypt and aes_encrypt are supported.	Security Functions
Function and operator	The character processing functions SHA, SHA1, and SHA2 are supported.	Character Processing Functions and Operators