This topic describes incompatibilities between MySQL databases and MySQL-compatible tenants of OceanBase Database when you change the length of an unconstrained column.
The following table describes the operations that you can perform to change the length of a column by executing the ALTER TABLE table_name MODIFY/CHANGE COLUMN DDL statement in a MySQL database and a MySQL-compatible tenant of OceanBase Database.
Note
In the table, a hyphen (-) indicates none.
| Column type in a MySQL database | Allowed operation | Column type in a MySQL-compatible tenant of OceanBase Database | Allowed operation |
|---|---|---|---|
| INT | Increase and decrease the length | INTEGER | Increase and decrease the length |
| TINYINT | Increase and decrease the length | TINYINT | Increase and decrease the length |
| SMALLINT | Increase and decrease the length | SMALLINT | Increase and decrease the length |
| MEDIUMINT | Increase and decrease the length | MEDIUMINT | Increase and decrease the length |
| BIGINT | Increase and decrease the length | BIGINT | Increase and decrease the length |
| BOOL | - | BOOLEAN | - |
| DECIMAL | Increase and decrease the length | DECIMAL | Increase the length |
| NUMERIC | Increase and decrease the length | NUMERIC | Increase the length |
| REAL | Increase and decrease the length | FLOAT | Increase and decrease the length |
| DOUBLE | Increase and decrease the length | DOUBLE | Increase and decrease the length |
| FLOAT | Increase and decrease the length | FLOAT | Increase and decrease the length |
| BIT | Increase and decrease the length | BIT | Increase and decrease the length |
| CHAR | Increase and decrease the length | CHAR | Increase the length |
| NCHAR | Increase and decrease the length | CHAR | Increase the length |
| VARCHAR | Increase and decrease the length | VARCHAR | Increase the length |
| BINARY | Increase and decrease the length | BINARY | - |
| VARBINARY | Increase and decrease the length | VARBINARY | Increase the length |
| LONG_VARBINARY | - | BLOB | - |
| YEAR | Increase and decrease the length | YEAR | Increase the length (the length is fixed to be 4 bytes) |
| DATE | - | DATE | - |
| TIME | Increase and decrease the length | TIME | Increase the length |
| TIMESTAMP | Increase and decrease the length | TIMESTAMP | Increase the length |
| DATETIME | Increase and decrease the length | DATETIME | Increase the length |
| TINYBLOB | - | TINYBLOB | - |
| MEDIUMBLOB | - | MEDIUMBLOB | - |
| BLOB | - | BLOB | - |
| LONGBLOB | - | LONGBLOB | - |
| TINYTEXT | - | TINYTEXT | - |
| MEDIUMTEXT | - | MEDIUMTEXT | - |
| TEXT | - | TEXT | - |
| LONGTEXT | - | LONGTEXT | - |
| ENUM | Increase and decrease the length | ENUM | Increase the length |
| SET | Increase and decrease the length | SET | Increase the length |
| JSON | - | JSON | - |
