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Re: How can I get a sum from specific fields in where clause?
Posted by: Peter Brawley
Date: April 08, 2022 12:11PM

A big part of improving from bad to good programming is learning how to write the requirement so clearly, a 12-year-old novice understands it instantly.

First, it's a design error to define a column as text when arithmetic will be done on its contents. It needs to be int or decimal.

Then, your statement of the requirement ...


WHERE srvid=1 AND if(QID <> GivenQID, TRUE, if(TheQuery, TRUE, FALSE)) = TRUE
TheQuery: SUM(Answer) of any specific MX >= GivenValue

... entails that the query know sum(`answer`) before it runs. Obviously not possible.

The requirement appears to be at least a 2-step ...

1 Find rows for which sum(`answer`) >= givenvalue. For this, you'll need to specify exactly how to define which rows are to be thus Grouped By.

2 Then apply the other criteria referenced above to those rows.

Here's a little toy table we could use for working this up ...

drop table if exists t;
create table t (srvid int, qid int, mx int, ma int, answer int );
insert into t values

Edited 1 time(s). Last edit at 04/08/2022 12:15PM by Peter Brawley.

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