MySQL query with avg and count greater than a value

Question

I have table tbl_emply containing fields Salary , DNO , and EID for each employ. I need to find average Salary of each DNO that has more than two employees.

I have tried queries like

1.  select avg(salary),DNO from tbl_emply where count(select * from tbl_emply group by(DNO)>2); 

2.  select avg(salary),DNO from tbl_emply group by(DNO); 

But these all gave me invalid use of group by. How to get the result?

Answer 1

Use HAVING

SELECT AVG(salary), DNO
FROM tbl_emply
GROUP BY DNO
HAVING COUNT(*) > 2

Answer 2

试试这个，

select avg(Salary),DNo from tbl_emply group by DNo having count(*)>2;