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How can I count unique records from a column in MySQL database?
For this, use aggregate function count(*) to count to GROUP BY to group. Let us first create a table −
mysql> create table DemoTable ( UserName varchar(100), UserPostMessage text ); Query OK, 0 rows affected (0.54 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable values('Chris','Hi');
Query OK, 1 row affected (0.09 sec)
mysql> insert into DemoTable values('David','Hello');
Query OK, 1 row affected (0.11 sec)
mysql> insert into DemoTable values('Chris','Awesome');
Query OK, 1 row affected (0.16 sec)
mysql> insert into DemoTable values('Chris','Amazing');
Query OK, 1 row affected (0.17 sec)
mysql> insert into DemoTable values('David','Nice Place');
Query OK, 1 row affected (0.11 sec)
mysql> insert into DemoTable values('Chris','Amazing');
Query OK, 1 row affected (0.12 sec)Display all records from the table using select statement −
mysql> select *from DemoTable;
This will produce the following output −
+----------+-----------------+ | UserName | UserPostMessage | +----------+-----------------+ | Chris | Hi | | David | Hello | | Chris | Awesome | | Chris | Amazing | | David | Nice Place | | Chris | Amazing | +----------+-----------------+ 6 rows in set (0.00 sec)
Here is the query to count unique records from a column in my MySQL database −
mysql> select UserName,count(DISTINCT UserPostMessage) AS NumberOfMessagesPostByUser from DemoTable group by UserName;
This will produce the following output −
+----------+----------------------------+ | UserName | NumberOfMessagesPostByUser | +----------+----------------------------+ | Chris | 3 | | David | 2 | +----------+----------------------------+ 2 rows in set (0.00 sec)
Updated on: 27-Sep-2019
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