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Difference Between MySql <> NULL and IS NOT NULL?
If you compare the <> operator with NULL value then you will get NULL value always and no result.
Let us see some examples for comparison −
mysql> select 10 <> NULL; +------------+ | 10 <> NULL | +------------+ | NULL | +------------+ 1 row in set (0.00 sec) mysql> select NULL <> NULL; +--------------+ | NULL <> NULL | +--------------+ | NULL | +--------------+ 1 row in set (0.00 sec) mysql> select 'Chris' <> NULL; +-----------------+ | 'Chris' <> NULL | +-----------------+ | NULL | +-----------------+ 1 row in set (0.00 sec) mysql> select '' <> NULL; +------------+ | '' <> NULL | +------------+ | NULL | +------------+ 1 row in set (0.00 sec)
Let us first create a table −
mysql> create table DemoTable846(Value int); Query OK, 0 rows affected (0.93 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable846 values(NULL); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable846 values(10); Query OK, 1 row affected (0.11 sec)
Display all records from the table using select statement −
mysql> select *from DemoTable846;
This will produce the following output −
+-------+ | Value | +-------+ | NULL | | 10 | +-------+ 2 rows in set (0.00 sec)
Following is the result for IS NOT NULL operator −
mysql> select *from DemoTable846 where Value IS NOT NULL;
This will produce the following output −
+-------+ | Value | +-------+ | 10 | +-------+ 1 row in set (0.00 sec)
Here is the result for <> operator. Following is the query −
mysql> select *from DemoTable846 where Value <> NULL; Empty set (0.00 sec)
Updated on: 03-Jul-2020
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