How to Declare a Variable in SQL and Assign a Value? | ninjasquad
SQL is a language that is used to manage relational databases. It provides a facility for easily declaring and using variables. We can use variables for storing temporary values in memory for performing calculations. In SQL variables can be used in the same way we use in any other programming language.
SQL Declare Variable
In SQL we use DECLARE statements for declaring variables. Let’s see its syntax:
DECLARE @variable_name data_type;
The above syntax is self explanatory so no need to explain.
Here I have declared a variable with the name marks and type int.
SQL Assign Variable
I hope you got the idea about declaring variables now let’s have a look at how to assign some value.
SET @variable_name = value;
The SET statement is used for assigning some value to a variable in SQL.
As we declared a variable and assigned a value to it, now let’s take a look at how to use it with a SELECT statement.
SELECT * FROM Student WHERE total_marks > @marks;
Here we are fetching data of students from the table Student whose total_marks are more than marks i.e. more than 80.
Please note that the variable declared inside a stored procedure can be used in that procedure only.
So we can say DECLARE and SET statements are used to declare and assign a variable in SQL. Below I have mentioned a video that can help you understand the concept easily.