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How to count distinct values in MySQL?
To count distinct values, you can use distinct in aggregate function count().
The syntax is as follows −
select count(distinct yourColumnName) as anyVariableName from yourTableName;
To understand the above concept, let us create a table. The following is the query to create a table −
mysql> create table DistinctDemo −> ( −> Name varchar(200) −> ); Query OK, 0 rows affected (0.58 sec)
For our example, let us insert duplicate records in the table. The query to insert records is as follows −
mysql> insert into DistinctDemo values('John');
Query OK, 1 row affected (0.15 sec)
mysql> insert into DistinctDemo values('Sam');
Query OK, 1 row affected (0.17 sec)
mysql> insert into DistinctDemo values('John');
Query OK, 1 row affected (0.12 sec)
mysql> insert into DistinctDemo values('Johnson');
Query OK, 1 row affected (0.13 sec)
mysql> insert into DistinctDemo values('John');
Query OK, 1 row affected (0.10 sec)
mysql> insert into DistinctDemo values('Johnson');
Query OK, 1 row affected (0.12 sec)
mysql> insert into DistinctDemo values('Sam');
Query OK, 1 row affected (0.14 sec)
mysql> insert into DistinctDemo values('Johnson');
Query OK, 1 row affected (0.10 sec)
Display all records with the help of select statement. The query to display all records is as follows −
mysql> select *from DistinctDemo;
The following is the output displaying some duplicate records −
+---------+ | Name | +---------+ | John | | Sam | | John | | Johnson | | John | | Johnson | | Sam | | Johnson | +---------+ 8 rows in set (0.00 sec)
Here is the query that can be used to count distinct values from the table −
mysql> select count(distinct Name) as DistinctValues from DistinctDemo;
The following is the output −
+----------------+ | DistinctValues | +----------------+ | 3 | +----------------+ 1 row in set (0.01 sec)
The result i3 tells that we have 3 distinct values in the table.
Updated on: 2019-07-30T22:30:24+05:30
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