MySQL 8.4 Release Notes
COLUMNS_EXTENSIONS 表提供有关为主存储引擎和辅助存储引擎定义的列属性的信息。The COLUMNS_EXTENSIONS table provides
information about column attributes defined for primary and
secondary storage engines.
Note
COLUMNS_EXTENSIONS 表保留以备将来使用。The COLUMNS_EXTENSIONS table is
reserved for future use.
COLUMNS_EXTENSIONS 表包含以下列：The COLUMNS_EXTENSIONS table has
these columns:
TABLE_CATALOG表所属的目录名称。该值始终为
def。The name of the catalog to which the table belongs. This value is alwaysdef.TABLE_SCHEMA表所属的模式（数据库）名称。The name of the schema (database) to which the table belongs.
TABLE_NAMETABLE_NAME表的名称。The name of the table.
COLUMN_NAMECOLUMN_NAME列名称。The name of the column.
ENGINE_ATTRIBUTEENGINE_ATTRIBUTE为主存储引擎定义的列属性。保留以备将来使用。Column attributes defined for the primary storage engine. Reserved for future use.
SECONDARY_ENGINE_ATTRIBUTESECONDARY_ENGINE_ATTRIBUTE为辅助存储引擎定义的列属性。保留以备将来使用。Column attributes defined for the secondary storage engine. Reserved for future use.