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.

The last two lines are important. In this example, if the user id in the primary table is modified or deleted, the change will cascade to the child table. This ensures … Continue reading Adding Foreign Keys after a table is created in SQL Server

Adding Checks after a table is created in SQL Server

Did you create a table, only to find that you need to add a check constraint? I created a quick example of how to add a check constraint after the table exists. In this example, we want to know if our user is alive or dead. 1 = alive, 0 = dead. Here is the code for SQL server: alter table dbo.Tbl_User_Table add constraint CK_User_Alive check (User_Alive in (0,1)) I don’t know if it will work with MySql, Oracle, etc, so check your documentation. Happy Coding! RudyRudy Rodarte is a SQL Server Database professional based in Austin, TX. Over his … Continue reading Adding Checks after a table is created in SQL Server