This topic describes the scenarios where CREATE TABLE DDL operations performed in a MySQL database can be converted by the DDL synchronization component of the data transmission service but cannot be performed in a MySQL tenant of OceanBase Database during data migration from the MySQL database to the MySQL tenant of OceanBase Database.
Define a generated column based on other generated columns
Use other generated columns in the CREATE TABLE DDL statement to define a new generated column.
MySQL databases: supported.
MySQL tenants of OceanBase Database: not supported.
Sample code:
CREATE TABLE group_by_t1
(a INT GENERATED ALWAYS AS (1) VIRTUAL,
b INT GENERATED ALWAYS AS (a) VIRTUAL,
c INT GENERATED ALWAYS AS (1) VIRTUAL);Create an index or a constraint
When you create a constraint, the column types supported in a MySQL database are different from those supported in a MySQL tenant of OceanBase Database. For more information, see Column types that are supported to create indexes or constraints.
Limits on creating a FOREIGN KEY constraint:
MySQL tenants of OceanBase Database: The referenced column in the parent table must have the UNIQUE KEY or PRIMARY KEY constraint when you create a foreign key.
The referenced column in the parent table is specified in the FOREIGN KEY constraint.
MySQL databases: The referenced column in the parent table must have a UNIQUE KEY, PRIMARY KEY, or KEY constraint when you create a foreign key.