DB2 Unique Constraint over multiple Columns

问题:

Is there a way to create a unique constraint over multiple columns like in Mysql?

UNIQUE KEY `uniqueKey` (`Field1`,`Field2`),

The only thing i have found is the unique keyword directly after the field.

Thanks in advance!

回答1:

You should be able to add a unique constraint as:

alter table t add constraint unq_field1_field2 unique(field1, field2)

As with other databases, this is almost exactly equivalent to creating an index. The difference is that the constraint is named -- which can be convenient for tracking constraints and understanding error messages.

回答2:

You should be able to create a multi-column index

 CREATE UNIQUE INDEX myindex
                      ON mytable (col1, col2 desc, col3)