Question

Table 1 : (Company)

ID Name
1  A
2  B
3  C

Each company (pk = ID) can have one or more employees.

Table 2 :  (Employee)  (CompanyID referencing ID)

CompanyID EmpID Name
1         1     Joe
1         2     Doe
1         3     Boe
2         4     Lou
3         5     Su  
3         6     Ram

Query :

select CompanyID, count(*) from Employee group by CompanyID having count(*) > 1; # Lists companies and their counts.

CompanyID count(*)
1         3  
3         2

For this query, I want just one result with the count of distinct CompanyIDs. So, ‘2’ in this case [Companies A and C].

In short, I am looking for number of companies with 2 or more employees.

Is there anyway to get the result without a temp table or a join? I am using MySQL.

Answer 1

Yes:

select count(*) from
(select CompanyID from Employee group by CompanyID having count(*) > 1) v

or for ranges:

select count(*) from
(select CompanyID from Employee group by CompanyID 
 having count(*) >= 5 and count(*) < 10) v