9.10.CREATE INDEX Statement

        : column opt_asc_desc
        | index_column_commalist ',' column opt_asc_desc

        : CLUSTERED
        | UNIQUE

        : index_option
        | index_option_list index_option

        : /* empty */
        | index_option_list

        : CREATE opt_index_option_list INDEX index
                ON new_table_name '(' index_column_commalist ')'

This creates an index on a table. Index names must be unique across a qualifier. The ascending / descending column attributes are recognized for compatibility but do not have any effect. The index is defined and populated at the execution of the statement. Pre-existing stored procedures and prepared statements will make use of the new index when appropriate.

The UNIQUE attribute enforces uniqueness of the specified columns across the table and subtables where the index is visible.

The CLUSTERED attribute is not recommended. It will cause keys to be unprefixed by key id, thus causing the key entries to be intermixed with entries of other CLUSTERED indices with adjacent values of key parts.

[Tip] See:

See the Free Text section on creating free text indices.