Question

I have 2 tables – an Account table and a Users table. Each account can have multiple users. I have a scenario where I want to execute a single query/join against these two tables, but I want all the Account data (Account.*) and only the first set of user data (specifically their name).

Instead of doing a ‘min’ or ‘max’ on my aggregated group, I wanted to do a ‘first’. But, apparently, there is no ‘First’ aggregate function in TSQL.

Any suggestions on how to go about getting this query? Obviously, it is easy to get the cartesian product of Account x Users:

 SELECT User.Name, Account.* FROM Account, User  WHERE Account.ID = User.Account_ID 

But how might I got about only getting the first user from the product based on the order of their User.ID ?

Answer 1

Rather than grouping, go about it like this…

select     *  from account a  join (     select          account_id,          row_number() over (order by account_id, id) -              rank() over (order by account_id) as row_num from user      ) first on first.account_id = a.id and first.row_num = 0