MySQL Select Rows where two columns do not have the same value?

You can use != operator from MySQL for this. The syntax is as follows:

SELECT *FROM yourTableName WHERE yourColumnName1 !=yourColumnName2 OR (yourColumnName1 IS NULL AND yourColumnName2IS NOT NULL) OR (yourColumnName2 IS NULL AND yourColumnName1 IS NOT NULL);

To understand the above syntax, let us create a table. The query to create a table is as follows:

mysql> create table selectTwoColumns    -> (    -> Id int NOT NULL AUTO_INCREMENT,    -> FirstNumber int,    -> SecondNumber int,    -> PRIMARY KEY(Id)    -> ); Query OK, 0 rows affected (0.87 sec)

Insert some records in the table using insert command. The query is as follows:

mysql> insert into selectTwoColumns(FirstNumber,SecondNumber) values(10,20); Query OK, 1 row affected (0.29 sec) mysql> insert into selectTwoColumns(FirstNumber,SecondNumber) values(30,40); Query OK, 1 row affected (0.16 sec) mysql> insert into selectTwoColumns(FirstNumber,SecondNumber) values(20,20); Query OK, 1 row affected (0.15 sec) mysql> insert into selectTwoColumns(FirstNumber,SecondNumber) values(50,60); Query OK, 1 row affected (0.18 sec) mysql> insert into selectTwoColumns(FirstNumber,SecondNumber) values(50,50); Query OK, 1 row affected (0.17 sec) mysql> insert into selectTwoColumns(FirstNumber,SecondNumber) values(70,NULL); Query OK, 1 row affected (0.14 sec)

Display all records from the table using select statement. The query is as follows:

mysql> select *from selectTwoColumns;

The following is the output:

+----+-------------+--------------+ | Id | FirstNumber | SecondNumber | +----+-------------+--------------+ |  1 |          10 |           20 | |  2 |          30 |           40 | |  3 |          20 |           20 | |  4 |          50 |           60 | |  5 |          50 |           50 | |  6 |          70 |         NULL | +----+-------------+--------------+ 6 rows in set (0.00 sec)

Here is the query to select rows where two columns do not have same value:

mysql> select *from selectTwoColumns    -> where FirstNumber!=SecondNumber    -> OR (FirstNumber IS NULL AND SecondNumber IS NOT NULL)    -> OR (SecondNumber IS NULL AND FirstNumber IS NOT NULL);

The following is the output:

+----+-------------+--------------+ | Id | FirstNumber | SecondNumber | +----+-------------+--------------+ |  1 |          10 | 20 | |  2 | 30 | 40 | |  4 | 50 | 60 | |  6 | 70 | NULL | +----+-------------+--------------+ 4 rows in set (0.00 sec)