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How to treat NULL as 0 and add columns in MySQL?
Use the concept of IFNULL() method to treat NULL as 0. Let us first create a table −
mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Value1 int, Value2 int ); Query OK, 0 rows affected (0.64 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable(Value1,Value2) values(10,20); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable(Value1,Value2) values(null,null); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable(Value1,Value2) values(40,null); Query OK, 1 row affected (0.18 sec)
Following is the query to display all records from the table using select statement −
mysql> select *from DemoTable;
This will produce the following output −
+----+--------+--------+ | Id | Value1 | Value2 | +----+--------+--------+ | 1 | 10 | 20 | | 2 | NULL | NULL | | 3 | 40 | NULL | +----+--------+--------+ 3 rows in set (0.00 sec)
Following is the query to treat NULL as 0 and add columns −
mysql> select ifnull(Value1,0)+ifnull(Value2,0) AS NULL_AS_ZERO from DemoTable;
This will produce the following output displaying the sum since all the NULL values were considered 0 for addition −
+--------------+ | NULL_AS_ZERO | +--------------+ | 30 | | 0 | | 40 | +--------------+ 3 rows in set (0.00 sec)
Updated on: 30-Jul-2019
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