How to select sum or 0 if no records exist in MySQL?

You can use aggregate function sum() inside COALESCE(). The below syntax returns the sum of all if the record exists otherwise 0 is returned. The syntax is as follows.

select COALESCE(sum(yourColumnName2), 0) AS anyVariableName from yourTableName where yourColumnName1 like '%yourValue%';

To understand the above syntax, let us create a table. The query to create a table is as follows.

mysql> create table SumDemo -> ( -> Words varchar(100), -> Counter int -> ); Query OK, 0 rows affected (0.93 sec)

Insert some records in the table using insert command. The query is as follows.

mysql> insert into SumDemo values('Are You There',10); Query OK, 1 row affected (0.16 sec) mysql> insert into SumDemo values('Are You Not There',15); Query OK, 1 row affected (0.13 sec) mysql> insert into SumDemo values('Hello This is MySQL',12); Query OK, 1 row affected (0.09 sec) mysql> insert into SumDemo values('Hello This is not MySQL',14); Query OK, 1 row affected (0.24 sec)

Display all records from the table using select statement. The query is as follows.

mysql> select *from SumDemo;

The following is the output.

+-------------------------+---------+ | Words                   | Counter | +-------------------------+---------+ | Are You There           | 10      | | Are You Not There       | 15      | | Hello This is MySQL     | 12      | | Hello This is not MySQL | 14      | +-------------------------+---------+ 4 rows in set (0.00 sec)

Here is the query that gives the total sum whenever record exist.

mysql> select COALESCE(sum(Counter), 0) AS SumOfAll from SumDemo where Words like '%hello%';

The following is the output.

+----------+ | SumOfAll | +----------+ | 26       | +----------+ 1 row in set (0.00 sec)

If record does not exist then you will get 0. The query is as follows.

mysql> select COALESCE(sum(Counter), 0) AS SumOfAll from SumDemo where Words like '%End of MySQL%';

The following is the output.

+----------+ | SumOfAll | +----------+ | 0       | +----------+ 1 row in set (0.00 sec)