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 ...

By using cascading referential integrity constraints, you can define the actions that SQL Server 2005 takes when a user tries to delete or update a key to which existing foreign keys point.

A check constraint in a database is a rule that ensures that data meets a specific condition by restricting what data can be stored in a column. An example could be when creating a table in SQL ...

In SQL we have three four major constraints - 'UNIQUE', 'FOREIGN KEY', 'CHECK' and 'NOT NULL'. Also we have non-standard ON CONFLICT clause, which propose what kind ...

When I am working with an Oracle database, I still find myself using SQL*Plus for many quick and dirty database queries. In particular, I often look up constraints in SQL*Plus. In this post ...

NOT NULL constraint denotes that we have to provide some value for that column . We cannot left it blank, we must have to provide some value to it. Below is the SQL query which enforces the ...