Implement MySQL CASE statement with WHEN clause

CASE statement with the WHEN clause is used to work around conditions. Following is the syntax−

select *,    case when yourCondition then yourStatement    when yourCondition then yourStatement    .    . else yourStatement from yourTableName;

Let us first create a table −

mysql> create table DemoTable    -> (    -> StudentName varchar(20),    -> StudentMarks int    -> ); Query OK, 0 rows affected (0.77 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable values('Chris',78); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values('Robert',88); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('Mike',75); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values('Sam',98); Query OK, 1 row affected (0.16 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable;

This will produce the following output −

+-------------+--------------+ | StudentName | StudentMarks | +-------------+--------------+ | Chris       |           78 | | Robert      |           88 | | Mike        |           75 | | Sam         |           98 | +-------------+--------------+ 4 rows in set (0.00 sec)

Here is the query to implement MySQL CASE WHEN −

mysql> select *,    -> case when StudentMarks > 90 then 'Very Good Score'    -> when StudentMarks > 80 then 'Good Score'    -> else    -> 'Not Good'    -> end as Status    -> from DemoTable;

This will produce the following output −

+-------------+--------------+-----------------+ | StudentName | StudentMarks |    Status       | +-------------+--------------+-----------------+ | Chris       |           78 | Not Good        | | Robert      |           88 | Good Score      | | Mike        |           75 | Not Good        | | Sam         |           98 | Very Good Score | +-------------+--------------+-----------------+ 4 rows in set (0.00 sec)