information_schema.columns.column_key

Note:

Index type. PRI for primary key, UNI for unique index, MUL for multiple index. A MySQL and MariaDB extension.

Note:

Index type. PRI for primary key, UNI for unique index, MUL for multiple index. A MySQL and MariaDB extension.

Note:

Whether this column is indexed. This field might have the following values:\n\nEmpty: This column is not indexed, or this column is indexed and is the second column in a multi-column non-unique index.\nPRI: This column is the primary key or one of multiple primary keys.\nUNI: This column is the first column of the unique index.\nMUL: The column is the first column of a non-unique index, in which a given value is allowed to occur for multiple times.