The FOREIGN KEY columns in the referencing table must be identical in definition with the keys in the referenced table. Corresponding columns must have the same data type and case sensitivity.
- For standard referential integrity, the COMPRESS option is not permitted on either the referenced or referencing column(s).
- Column level constraints are not compared.
- A one-column FOREIGN KEY cannot reference a single column in a multicolumn primary or unique key—the foreign and primary/unique key must contain the same number of columns.