I am relatively new to SSMS. I am attempting to write a query to sum balances with specific account numbers, and then subtract the sum of the 2nd group from the sum of the first group. I am only concerned with the totals of the underlying balances, but need those balances based on the account numbers. Here's an example of how the data is structured:

AcctNo BAL

123 11

234 22

345 33

456 44

678 55

789 66

I would like to sum the balances of group one, and group 2, and subtract group 2 from group 1. My initial attempts were as follows:

Declare @Bal1 INT

Declare @Bal2 INT

Select @Bal1 = Sum(Bal)

From XXX

Where Acctno In ('123','234','345')

Select@Bal2 = sum(Bal)

From XXX

Where Acctno IN ('678','789')

@Bal1 - @Bal2

Any insight you can provide would be greatly appreciated. Thank you.