columns
columns
contains information about all table columns (or view columns).
note
The metadata of synchronous materialized views is not recorded in columns
. You can access it by executing SHOW PROC '/dbs/db/table/index_schema'
.
The following fields are provided in columns
:
Field | Description |
---|---|
TABLE_CATALOG | The name of the catalog to which the table containing the column belongs. This value is always NULL . |
TABLE_SCHEMA | The name of the database to which the table containing the column belongs. |
TABLE_NAME | The name of the table containing the column. |
COLUMN_NAME | The name of the column. |
ORDINAL_POSITION | The ordinal position of the column within the table. |
COLUMN_DEFAULT | The default value for the column. This is NULL if the column has an explicit default of NULL , or if the column definition includes no DEFAULT clause. |
IS_NULLABLE | The column nullability. The value is YES if NULL values can be stored in the column, NO if not. |
DATA_TYPE | The column data type. The DATA_TYPE value is the type name only with no other information. The COLUMN_TYPE value contains the type name and possibly other information such as the precision or length. |
CHARACTER_MAXIMUM_LENGTH | For string columns, the maximum length in characters. |
CHARACTER_OCTET_LENGTH | For string columns, the maximum length in bytes. |
NUMERIC_PRECISION | For numeric columns, the numeric precision. |
NUMERIC_SCALE | For numeric columns, the numeric scale. |
DATETIME_PRECISION | For temporal columns, the fractional seconds precision. |
CHARACTER_SET_NAME | For character string columns, the character set name. |
COLLATION_NAME | For character string columns, the collation name. |
COLUMN_TYPE | The column data type. The DATA_TYPE value is the type name only with no other information. The COLUMN_TYPE value contains the type name and possibly other information such as the precision or length. |
COLUMN_KEY | Whether the column is indexed:
COLUMN_KEY values applies to a given column of a table, COLUMN_KEY displays the one with the highest priority, in the order PRI , UNI , DUP .A UNIQUE index may be displayed as PRI if it cannot contain NULL values and there is no PRIMARY KEY in the table. A UNIQUE index may display as MUL if several columns form a composite UNIQUE index; although the combination of the columns is unique, each column can still hold multiple occurrences of a given value. |
EXTRA | Any additional information that is available about a given column. |
PRIVILEGES | The privileges you have for the column. |
COLUMN_COMMENT | Any comment included in the column definition. |
COLUMN_SIZE | |
DECIMAL_DIGITS | |
GENERATION_EXPRESSION | For generated columns, displays the expression used to compute column values. Empty for nongenerated columns. |
SRS_ID | This value applies to spatial columns. It contains the column SRID value that indicates the spatial reference system for values stored in the column. |