Is there a way to add a constraint between tables that would prevent a record from being deleted from table1 if it exists in table2, but table2 does not have to have an entry from table1.
Example: Table1 is sub_department information with an id field. Table2 is a department configuration table. Table2 has dept_id and sub_dept_id. Some configurations are only for the combination dept_id and sub_dept_id so a matching record must exist in the department table and sub-department table for corresponding id's. Since it is possible only the department has configuration information then sub_dept_id would default to zero. (not in the sub-department table). Because of this I can not add a normal constraint that would stop a sub_department from being removed if it is used in the configuration table.
Thoughts? Thanks!
Example: Table1 is sub_department information with an id field. Table2 is a department configuration table. Table2 has dept_id and sub_dept_id. Some configurations are only for the combination dept_id and sub_dept_id so a matching record must exist in the department table and sub-department table for corresponding id's. Since it is possible only the department has configuration information then sub_dept_id would default to zero. (not in the sub-department table). Because of this I can not add a normal constraint that would stop a sub_department from being removed if it is used in the configuration table.
Thoughts? Thanks!