- All Implemented Interfaces:
- AlterTableCommand
public class AddUniqueConstraintCommand
extends Object
implements AlterTableCommand
Represents a unique constraint on a set of columns. Beware columns that allow null values! On SQL Server and Oracle,
nulls are distinct values (and so constraints over them will prevent two rows containing nulls in those columns).
On MySQL nulls will cause the constraint to be ignored, no matter the values in any other constrained columns. On DB2,
nullable columns cannot have unique constraints at all.