constraints and relationships using SQL server part-9 #sqlserver #sqlqueries #sql #sqltraining

-constraints are tell the SQL to control the data that can be put into the columns. example-unique ,check ,primary key and others
-Relationship is an association between tables. The most common relationship types are one to one ,one to many ,many to many.
What are the 6 types of constraints in SQL Server?

The following constraints are commonly used in SQL:
NOT NULL - Ensures that a column cannot have a NULL value.
UNIQUE - Ensures that all values in a column are different.
PRIMARY KEY - A combination of a NOT NULL and UNIQUE . ...
FOREIGN KEY - Prevents actions that would destroy links between tables