Mysql query using where and group by clause

Question

I have the following table.

mysql> select * from consumer9; +------------+--------------+-------------------+ | Service_ID | Service_Type | consumer_feedback | +------------+--------------+-------------------+ |        100 | Computing    |                -1 | |         35 | Printer      |                 0 | |         73 | Computing    |                -1 | |         50 | Data         |                 0 | +------------+--------------+-------------------+ 

I want to use GROUP BY clause in my project. I am getting an error when I am using the query:

SELECT  Service_ID, Service_Type, SUM(consumer_feedback)  FROM consumer9  GROUP BY Service_ID  WHERE Service_Type=Printer; 

Error

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'where Service_Type=Printer' at line 1

Answer 1

The following query should work.

select Service_ID, Service_Type, sum(consumer_feedback)  from consumer9  where Service_Type=Printer group by Service_ID, Service_Type; 

Remember, the where clause goes before the group by clause and all non-aggregated terms in the select part will have to be present in the group by clause.