referential integrity in as400

Any field in a table that is declared a foreign key can contain only values from a parent table's primary key.
http://en.wikipedia.org/wiki/Referential_integrity

Add PF Constraint (ADDPFCST)

The Add Physical File Constraint (ADDPFCST) command can be used to add constraint relationships to a specified physical file. The four types of constraint relationships that you can add are referential constraints, unique constraints, primary key constraints and check constraints. All constraints are defined at the file level.
http://publib.boulder.ibm.com/infocenter/iseries/v5r4/index.jsp?topic=%2Fcl%2Faddpfcst.htm 

http://itknowledgeexchange.techtarget.com/itanswers/cpf4328-file-constraint-with-restrict-rules/


video tutorial(i am not good in English but it helpful to you)