How to convert MySQL null to 0 using COALESCE() function?

You can use the COALESCE() function to convert MySQL null to 0

SELECT COALESCE(yourColumnName,0) AS anyAliasName FROM yourTableName;

Let us first create a table. The query to create a table is as follows

mysql> create table convertNullToZeroDemo
   -> (
   -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   -> Name varchar(20),
   -> Salary int
   -> );
Query OK, 0 rows affected (1.28 sec)

Insert some records in the table using insert command.

The query is as follows

mysql> insert into convertNullToZeroDemo(Name,Salary) values('John',NULL);
Query OK, 1 row affected (0.20 sec)
mysql> insert into convertNullToZeroDemo(Name,Salary) values('Carol',5610);
Query OK, 1 row affected (0.10 sec)
mysql> insert into convertNullToZeroDemo(Name,Salary) values('Bob',NULL);
Query OK, 1 row affected (0.15 sec)
mysql> insert into convertNullToZeroDemo(Name,Salary) values('David',NULL);
Query OK, 1 row affected (0.12 sec)

Display all records from the table using select statement.

The query is as follows

mysql> select *from convertNullToZeroDemo;

The following is the output

+----+-------+--------+
| Id | Name  | Salary |
+----+-------+--------+
| 1  | John  | NULL   |
| 2  | Carol | 5610   |
| 3  | Bob   | NULL   |
| 4  | David | NULL   |
+----+-------+--------+
4 rows in set (0.05 sec)

Here is the query to convert MySQL NULL to 0 using COALESCE() function

mysql> select coalesce(Salary,0) as `CONVERT_NULL _TO_0` from convertNullToZeroDemo;

The following is the output

+--------------------+
| CONVERT_NULL _TO_0 |
+--------------------+
| 0                  |
| 5610               |
| 0                  |
| 0                  |
+--------------------+
4 rows in set (0.00 sec)