Question

I am developing a system using MySQL queries written by another programmer, and am adapting his code.

I have three questions:

1.

One of the queries has this select statement:

SELECT
   [...]
   AVG(mytable.foo, 1) AS 'myaverage'`, 

Is the 1 in AVG(mytable.foo, 1) AS 'myaverage' legitimate? I can find no documentation to support its usage?

2.

The result of this gives me average values to 2 decimal places, why?.

3.

I am using this to create a temp table. So:

(SELECT
    [...]
    AVG(`mytable`.`foo`, 1) AS `myaverage`,
FROM
    [...]
WHERE
    [...]
GROUP BY
    [...])
UNION
(SELECT
    [...]
FROM
    [...]
WHERE
    [...]
GROUP BY
    [...])
) AS `tmptable`
ORDER BY
    `tmptable`.`myaverage` DESC

When I sort the table on this column I get output which indicates that this average is being stored as a string, so the result is like:

9.3

11.1

In order to get around this what should I use?

Should I be using CAST or CONVERT, as DECIMAL (which I read is basically binary), BINARY itself, or UNSIGNED?

Or, is there a way to state that myaverage should be an integer when I name it in the AS statement?

Something like:

SELECT
    AVG(myaverage) AS `myaverage`, INT(10)

Thanks.

Answer 1

Just for anyone who’s interested, I must have deleted or changed my predecessors code so this AVG question was incorrect. The correct code was ROUND(AVG(myaverage),1). Apologies to those who scrathed their heads over my stupidity.