Count two different columns in a single query in MySQL?
You can use CASE statement to count two different columns in a single query. To understand the concept, let us first create a table. The query to create a table is as follows.
mysql> create table CountDifferentDemo
- > (
- > ProductId int NOT NULL AUTO_INCREMENT PRIMARY KEY,
- > ProductName varchar(20),
- > ProductColor varchar(20),
- > ProductDescription varchar(20)
- > );
Query OK, 0 rows affected (1.06 sec)
Insert some records in the table using insert command.
The query is as follows
mysql> insert into CountDifferentDemo(ProductName,ProductColor,ProductDescription) values('Product-1','Red','Used');
Query OK, 1 row affected (0.46 sec)
mysql> insert into CountDifferentDemo(ProductName,ProductColor,ProductDescription) values('Product-1','Blue','Used');
Query OK, 1 row affected (0.17 sec)
mysql> insert into CountDifferentDemo(ProductName,ProductColor,ProductDescription) values('Product-2','Green','New');
Query OK, 1 row affected (0.12 sec)
mysql> insert into CountDifferentDemo(ProductName,ProductColor,ProductDescription) values('Product-2','Blue','New');
Query OK, 1 row affected (0.14 sec)
mysql> insert into CountDifferentDemo(ProductName,ProductColor,ProductDescription) values('Product-3','Green','New');
Query OK, 1 row affected (0.21 sec)
mysql> insert into CountDifferentDemo(ProductName,ProductColor,ProductDescription) values('Product-4','Blue','Used');
Query OK, 1 row affected (0.20 sec)Display all records from the table using select statement.
The query is as follows
mysql> select *from CountDifferentDemo;
The following is the output
+-----------+-------------+--------------+--------------------+
| ProductId | ProductName | ProductColor | ProductDescription |
+-----------+-------------+--------------+--------------------+
| 1 | Product-1 | Red | Used |
| 2 | Product-1 | Blue | Used |
| 3 | Product-2 | Green | New |
| 4 | Product-2 | Blue | New |
| 5 | Product-3 | Green | New |
| 6 | Product-4 | Blue | Used |
+-----------+-------------+--------------+--------------------+
6 rows in set (0.01 sec)
Here is the query to count two different columns in a single query i.e. we are counting the occurrence of a particular color “Red” and description “New”
mysql> select ProductName,
- > SUM(CASE WHEN ProductColor = 'Red' THEN 1 ELSE 0 END) AS Color,
- > SUM(CASE WHEN ProductDescription = 'New' THEN 1 ELSE 0 END) AS Desciption
- > from CountDifferentDemo
- > group by ProductName;
The following is the output
+-------------+-------+------------+
| ProductName | Color | Desciption |
+-------------+-------+------------+
| Product-1 | 1 | 0 |
| Product-2 | 0 | 2 |
| Product-3 | 0 | 1 |
| Product-4 | 0 | 0 |
+-------------+-------+------------+
4 rows in set (0.12 sec)
Published on 19-Mar-2019 17:02:40
