Adding Foreign Keys after a table is created in SQL Server
Well, you knew exactly what you needed when you created a table. Only now when you created a child table, the child table does not update with the information from your main table. Or worse you deleted something from your primary table and it still lives in the child table. You need a foreign key, my friend. This is how you define one after you’ve created your table. ALTER TABLE My_Child_Table ADD CONSTRAINT FK_User_ID FOREIGN KEY ( User_ID_In_Child_Table ) REFERENCES My_Primary_Table ( User_ID_In_Primary_Table ) ON DELETE CASCADE ON UPDATE CASCADE The last two lines are important. In this example, if … Continue reading Adding Foreign Keys after a table is created in SQL Server