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How to use count with CASE condition in a MySQL query?
Use CASE WHEN for this in MySQL and set CASE condition inside the COUNT() method to count. Let us first create a table −
mysql> create table DemoTable1374 -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Name varchar(20), -> Score int -> ); Query OK, 0 rows affected (0.61 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable1374(Name,Score) values('Chris',45);
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable1374(Name,Score) values('David',78);
Query OK, 1 row affected (0.10 sec)
mysql> insert into DemoTable1374(Name,Score) values('Bob',45);
Query OK, 1 row affected (0.12 sec)
mysql> insert into DemoTable1374(Name,Score) values('Mike',75);
Query OK, 1 row affected (0.10 sec)
mysql> insert into DemoTable1374(Name,Score) values('Carol',45);
Query OK, 1 row affected (0.09 sec)
mysql> insert into DemoTable1374(Name,Score) values('Adam',89);
Query OK, 1 row affected (0.18 sec)Display all records from the table using select statement −
mysql> select * from DemoTable1374;
This will produce the following output −
+----+-------+-------+ | Id | Name | Score | +----+-------+-------+ | 1 | Chris | 45 | | 2 | David | 78 | | 3 | Bob | 45 | | 4 | Mike | 75 | | 5 | Carol | 45 | | 6 | Adam | 89 | +----+-------+-------+ 6 rows in set (0.00 sec)
Following is the query for CASE WHEN to set condition and count −
mysql> select count( case when Score=45 then 1 else NULL end) as SpecificCondition from DemoTable1374;
This will produce the following output −
+-------------------+ | SpecificCondition | +-------------------+ | 3 | +-------------------+ 1 row in set (0.00 sec)
Updated on: 11-Nov-2019
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