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How to find records with a null value in a set of columns with MySQL
For this, use the concept of GREATEST(). Let us first create a table −
mysql> create table DemoTable1862 ( Value1 int, Value2 int, Value3 int, Value4 int ); Query OK, 0 rows affected (0.00 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable1862 values(43,34,56,42); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1862 values(NULL,78,65,NULL); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1862 values(110,NULL,78,NULL); Query OK, 1 row affected (0.00 sec)
Display all records from the table using select statement −
mysql> select * from DemoTable1862;
This will produce the following output −
+--------+--------+--------+--------+ | Value1 | Value2 | Value3 | Value4 | +--------+--------+--------+--------+ | 43 | 34 | 56 | 42 | | NULL | 78 | 65 | NULL | | 110 | NULL | 78 | NULL | +--------+--------+--------+--------+ 3 rows in set (0.00 sec)
Here is the query to find records with a null value in a set of columns −
mysql> select * from DemoTable1862 where greatest(Value1,Value2,Value3,Value4) IS NULL;
This will produce the following output −
+--------+--------+--------+--------+ | Value1 | Value2 | Value3 | Value4 | +--------+--------+--------+--------+ | NULL | 78 | 65 | NULL | | 110 | NULL | 78 | NULL | +--------+--------+--------+--------+ 2 rows in set (0.00 sec)
Updated on: 26-Dec-2019
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