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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)
Updated on: 29-Jun-2020
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