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How to count the number of occurrences of a specific value in a column with a single MySQL query?
For this, you can use GROUP BY clause along with IN(). Let us first create a table −
mysql> create table DemoTable -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Name varchar(100) -> ); Query OK, 0 rows affected (0.87 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable(Name) values('John');
Query OK, 1 row affected (0.23 sec)
mysql> insert into DemoTable(Name) values('Chris');
Query OK, 1 row affected (0.12 sec)
mysql> insert into DemoTable(Name) values('David');
Query OK, 1 row affected (0.23 sec)
mysql> insert into DemoTable(Name) values('Chris');
Query OK, 1 row affected (0.17 sec)
mysql> insert into DemoTable(Name) values('Chris');
Query OK, 1 row affected (0.21 sec)
mysql> insert into DemoTable(Name) values('John');
Query OK, 1 row affected (0.10 sec)
mysql> insert into DemoTable(Name) values('Carol');
Query OK, 1 row affected (0.20 sec)
mysql> insert into DemoTable(Name) values('Sam');
Query OK, 1 row affected (0.19 sec)Display all records from the table using select statement −
mysql> select *from DemoTable;
This will produce the following output −
+----+-------+ | Id | Name | +----+-------+ | 1 | John | | 2 | Chris | | 3 | David | | 4 | Chris | | 5 | Chris | | 6 | John | | 7 | Carol | | 8 | Sam | +----+-------+ 8 rows in set (0.00 sec)
Now, count the number of occurrences of a specific value in a column with a single query −
mysql> select Name,count(*) AS Occurrences from DemoTable
-> where Name in('John','Chris') group by Name;This will produce the following output −
+-------+-------------+ | Name | Occurrences | +-------+-------------+ | John | 2 | | Chris | 3 | +-------+-------------+ 2 rows in set (0.00 sec)
Updated on: 30-Jul-2019
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