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Add a column count in a MySQL query on the basis of last name records?
Let us first create a table −
mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, FirstName varchar(100), LastName varchar(100) ); Query OK, 0 rows affected (1.00 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable(FirstName,LastName) values('David','Miller');
Query OK, 1 row affected (0.35 sec)
mysql> insert into DemoTable(FirstName,LastName) values('Carol','Miller');
Query OK, 1 row affected (0.37 sec)
mysql> insert into DemoTable(FirstName,LastName) values('John','Doe');
Query OK, 1 row affected (0.21 sec)Display all records from the table using select statement −
mysql> select *from DemoTable;
This will produce the following output −
+----+-----------+----------+ | Id | FirstName | LastName | +----+-----------+----------+ | 1 | David | Miller | | 2 | Carol | Miller | | 3 | John | Doe | +----+-----------+----------+ 3 rows in set (0.00 sec)
Following is the query to add a column count for last name records like “Miller” is appearing 2 times::
mysql> select Id, FirstName, LastName,Count from DemoTable tbl1 JOIN (select count(*) as Count, LastName from DemoTable GROUP BY LastName) tbl2 using(LastName);
This will produce the following output −
+----+-----------+----------+-------+ | Id | FirstName | LastName | Count | +----+-----------+----------+-------+ | 1 | David | Miller | 2 | | 2 | Carol | Miller | 2 | | 3 | John | Doe | 1 | +----+-----------+----------+-------+ 3 rows in set (0.00 sec)
Updated on: 30-Sep-2019
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