Creation of relationships with referential constraints

Referential integrity is a condition in which all intended references from data in one table column to data in another table column are valid. By using referential constraints, you can define relationships between entities that you define in Db2.

Organizations that choose to enforce referential constraints have at least one thing in common. They need to ensure that values in one column of a table are valid with respect to other data values in the database.

For example:

• A manufacturing company wants to ensure that each part in a PARTS table identifies a product number that equals a valid product number in the PRODUCTS table.
• A company wants to ensure that each value of DEPT in the EMP table equals a valid DEPTNO value in the DEPT table.

If the DBMS did not support referential integrity, programmers would need to write and maintain application code that validates the relationship between the columns. Some programs might not enforce business rules, even though it is recommended.

This programming task can be complex because of the need to make sure that only valid values are inserted or updated in the columns. When the DBMS supports referential integrity, as Db2 does, programmers avoid some complex programming tasks and can be more productive in their other work.