columns

columns contains information about all table columns (or view columns).

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: If `COLUMN_KEY` is empty, the column either is not indexed or is indexed only as a secondary column in a multiple-column, nonunique index. If `COLUMN_KEY` is `PRI`, the column is a `PRIMARY KEY` or is one of the columns in a multiple-column `PRIMARY KEY`. If `COLUMN_KEY` is `UNI`, the column is the first column of a `UNIQUE` index. (A `UNIQUE` index permits multiple `NULL` values, but you can tell whether the column permits `NULL` by checking the `Null` column.) If `COLUMN_KEY` is `DUP`, the column is the first column of a nonunique index in which multiple occurrences of a given value are permitted within the column. If more than one of the `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.