Restrictions on Using the Single-Column Constraint Format
The single-column constraint format cannot specify a constraint that involves more than one column. Thus, you cannot use the single-column constraint format to define a composite key. For information on multiple-column constraints, see Multiple-Column Constraint Format.
You cannot define a referential constraint or a unique constraint on any column of a RAW table. Only NOT NULL or NULL constraints are supported on RAW tables.
You cannot place unique, primary-key, or referential constraints on BLOB, BYTE, CLOB, or TEXT columns. You can, however, check for NULL or non-NULL values on BYTE or TEXT columns with a check constraint.
If the constraint is on a column that stores encrypted data, HCL OneDB™ cannot enforce the constraint.