In this article, I would like to show the most commonly used case expressions with update statements in SQL Server. CASE is the special scalar expression or conditional statement in the SQL language which returns a single value based on the evaluation of a statement. In this article, you use case with an update statement. So let's have a look at a practical example of how to use a case with Update statement in SQL Server 2012. The example is developed in SQL Server 2012 using the SQL Server Management Studio. We'll start by walking through a simple case statement.
Creating a Table in SQL Server
Case Statement with Simple Expression
The Simple Case expression checks only for equivalent values and cannot contain Boolean expressions. A Simple Case Expression looks for the first expression in the list of all the "when" clauses that matches the expression and evaluates the corresponding when clause. If there is no match, then the else clause is evaluated (if it exists). The general syntax of the Simple CASE expression is:
CASE expression
WHEN exp_1 THEN result_1
[WHEN exp_2 THEN result_2]
[..................]
[WHEN exp_n THEN result_n]
[ELSE expression]
END
Example
DECLARE @Name varchar(50)
SET @Name = 'Rohatash'
SELECT
Case @Name
WHEN 'Deepak' THEN 'Name Deepak'
WHEN 'Manoj' THEN 'Name Found Manoj'
WHEN 'Rohatash' THEN 'Name Found Rohatash'
ELSE 'Name not Found'
END
Case Expression with Select Statement
The Searched Case expression contains Boolean expressions or comparison operators. In the following example we will see how to use a searched expression with comparison operators.
The general syntax of the searched CASE expression is:
CASE
WHEN condition_1 THEN result_1
[WHEN condition_2 THEN result_2]
[..................]
[WHEN condition_n THEN result_n]
[ELSE expression]
[else result_n]
END
Example
Creating a Table in SQL Server
create table student
(
stu_id int,
stu_name varchar(20),
marks int
);
Now inserting rows values into the student table:
Insert into student values('101','ravi','65');
Insert into student values('102','sumit','32');
Insert into student values('103','rekha','76');
Insert into student values('104','Yong','34');
Insert into student values('105','Hem','78');
The Student table looks like this:
Output
![Table-in-SQL-Server.jpg]()
In the above table the student's Id, Name and their marks are given. Now I want the following output with the help of a CASE statement:
Stu_Id Stu_Name Marks Remarks Grade
101 Ravi 65 Pass A
102 Sumit 32 Fail E
103 Rekha 76 Pass A +
104 Yong 34 Pass E
105 Hem 78 Pass A+
Using CASE Expression
Select Stu_Id,Stu_Name,Marks,
Case When Marks > 32 Then 'Pass' Else 'Fail'
End as Remarks,
Case When Marks >= 76 Then 'A+'
When Marks >= 65 Then 'A'
When Marks < 35 Then 'E'
End as Grade
From Student
Output
![searched-expression-in-sql-server.jpg]()
Using CASE Expression with Update Statement
In the following table the student's Id, Name and their marks and Remarks are given.
Stu_Id Stu_Name Marks Remarks
101 Ravi 65 Pass
102 Sumit 32 Fail
103 Rekha 76 Pass
104 Yong 34 Pass
105 Hem 78 Pass
Now I want the following output with the help of a CASE statement:
Stu_Id Stu_Name Marks Remarks
101 Ravi 65 Fail
102 Sumit 32 Pass
103 Rekha 76 Fail
104 Yong 34 Fail
105 Hem 78 Fail
You can see in the above remarks column of the student table which contain Records as Pass or Fail. Your task is to write a query which will change the Remarks Pass to Fail and Fail to Pass. Now I want the preceding output with the help of a CASE statement:
update Student
set Remarks =
CASE WHEN Remarks='Pass' THEN 'Fail'
When Remarks='Fail' THEN 'Pass'
End
select * from Student
Now press F5 to execute the query.
Output
![Case-with-update-statement-in-SQL-Server.jpg]()