A rule in SQL is used to specify a restriction on the values for a column or a user defined value.
There are two statements which we are used in Rules:
:- CREATE RULE
:- DROP RULE
Syntax of CREATE RULE:
CREATE RULE rule_name as Conditional_Expression
Here rule_name is the name of the Rule and Conditional_Expression is the condition that defines the Rule.
CREATE RULE countryname as @countryname IN ('India','USA');
DROP RULE is used when we want to drop the RULE
Ex:
DROP RULE countryname