Use MySQL JOIN to select MySQL rows where column contains same data in more than one record. Let us first create a table −
mysql> create table DemoTable ( UserId int, UserName varchar(20) ); Query OK, 0 rows affected (0.54 sec)
Insert records in the table using insert command −
mysql> insert into DemoTable values(10,'John'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values(11,'Sam'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values(12,'Larry'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values(13,'David'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values(14,'Larry'); Query OK, 1 row affected (0.10 sec)
Display records from the table using select command −
mysql> select *from DemoTable;
This will produce the following output −
+--------+----------+ | UserId | UserName | +--------+----------+ | 10 | John | | 11 | Sam | | 12 | Larry | | 13 | David | | 14 | Larry | +--------+----------+ 5 rows in set (0.00 sec)
Following is the query to select rows where a column contains same data in more than one record −
mysql> SELECT DISTINCT tbl1.* FROM DemoTable tbl1 JOIN DemoTable tbl2 on tbl2.UserId <> tbl1.UserId AND tbl2.UserName=tbl1.UserName;
This will produce the following output −
+--------+----------+ | UserId | UserName | +--------+----------+ | 14 | Larry | | 12 | Larry | +--------+----------+ 2 rows in set (0.14 sec)