Can we use query in Concat

[saadi06]

Hi,
I have a question that can we use a mysql query in Concat clause. I want to make a query like this

 SELECT CONCAT(AVG(value),'-',(select Count(UserId) as counts from user_details )) as `Average` from surveyuseranswer

Now I want to count number of users and concat it with the average value. My query runs but it returns me nothing. Can anyone help me that where I am wrong.
Thanks in advance.

[dcdruck]

I think you should be able to do that. Are you getting an error or just an empty resultset?

[saadi06]

I am getting an empty result but no error.I wanted to know that why the result is coming empty because the result should not be empty as there I run the count query alone it displays me the count number.

[dcdruck]

What if you run the outer query alone without the inner query? Do you get results then?

SELECT AVG(value) as `Average` from surveyuseranswer