Here is a list of limitations that apply to 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.