Details: Adding referential constraints

 

Consider these limitations when adding referential constraints.

• A parent file must be a physical file.

• A parent file can have a maximum of one member, MAXMBR(1).

• A dependent file must be a physical file.

• A dependent file can have a maximum of one member, MAXMBR(1).

• You can define a constraint when both or either of the dependent and the parent files have zero members. A constraint cannot be established unless both files have a member.

• A file can have a maximum of one primary key, but might have many unique constraints.

• There is a maximum of 300 constraint relations per file. This maximum value is the sum of:

  • The referential constraints whether participating as a parent or a dependent, and whether the constraints are defined or established.

  • The unique constraints, which includes the primary key constraint.

  • The check constraints.

• Only externally described files are allowed in referential constraints. Source files are not allowed. Program described files are not allowed.

• Files with insert, update, or delete capabilities are not allowed in *RESTRICT relationships.

• Constraint names must be unique in a library.

• You cannot add constraints to files in the QTEMP library.

• You cannot add a referential constraint where the parent file is in one ASP and the dependent file is in a different ASP.

 

Parent topic:

Adding referential constraints