How to use Assignment Operators in MySQL

Notes:

Assignment Operators in MySQL:
( := )
- is used to assign a value to a variable; which then can be referred in multiple queries
- is basically used in select query

( = )
- is used to assign a value to a variable, a column and check for equality
- is basically used with set clause and where clause

Basic Syntax: for creating a variable and assigning value to it
@variable_name := / = value

Example code:
set @a := 10;
set @b := 20;
set @c := @a + @b;
select @a; # 10
select @b; # 20
select @c; # 30

set @d = 100;
set @e = 200;
set @f = @d + @e;
select @d; # 100
select @e; # 200
select @f; # 300

Example code:
select @s_id := id from tbl_student where name = ‘ramesh’;
delete from tbl_receipt where stud_id = @s_id;
delete from tbl_student where id = @s_id;

Example code:
update tbl_faculty set salary = 3000 where name = ‘suresh’;

Interview Questions: