Constraints that applied to column are called column level constraints whereas constraints that applied ... but only one PRIMARY KEY constraint in a table. SQL UNIQUE Constraint syntax Below SQL query ...

and would do well to have constraints such as this one applied in a business logic layer rather than at this level, since you would actually need as many columns in the "orders" table as types of ...

After you have created and populated a table, you may need to modify the table's design. To do so, use the ALTER TABLE statement. Be aware that altering an existing table's structure may cause you to ...

Cascading referential integrity constraints are foreign key constraints that tell SQL ... columns affected must allow NULL values. If a delete statement affects one or more rows in a foreign key ...

Constraints in SQL are used to define rules for the table and columns in a database and also make sure that data are accurate and trusted in the database. Constraints are responsible for the ...