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Fetch maximum value from multiple columns with null and non-null values?
For this, you can use COALESCE(). For the maximum value, use GREATEST() in MySQL. Let us first create a table −
mysql> create table DemoTable -> ( -> Value1 int, -> Value2 int, -> Value3 int -> ); Query OK, 0 rows affected (0.61 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable values(NULL,80,76); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values(NULL,NULL,100); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values(56,NULL,45); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values(56,120,90); 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 −
+--------+--------+--------+ | Value1 | Value2 | Value3 | +--------+--------+--------+ | NULL | 80 | 76 | | NULL | NULL | 100 | | 56 | NULL | 45 | | 56 | 120 | 90 | +--------+--------+--------+ 4 rows in set (0.00 sec)
Following is the query to fetch the maximum value from multiple columns −
mysql> select greatest(coalesce(Value1,0),coalesce(Value2,0),coalesce(Value3,0)) from DemoTable;
This will produce the following output −
+--------------------------------------------------------------------+ | greatest(coalesce(Value1,0),coalesce(Value2,0),coalesce(Value3,0)) | +--------------------------------------------------------------------+ | 80 | | 100 | | 56 | | 120 | +--------------------------------------------------------------------+ 4 rows in set (0.00 sec)
Updated on: 17-Dec-2019
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