T-SQL check empty recordset

In many situations when writing procedures in T-SQL for Micrososft SQL server, we set a variable as a result of a query and then before using that variable (specially for numeric results) want to check if that query returned any results at all. This is how we can do it

CREATE PROCEDURE [dbo].[GetClientOpeningBalance]

(

@client_id bigint,

@transdate datetime

)

AS

SET NOCOUNT OFF;

DECLARE @balance_c AS float

DECLARE @balance_t AS float

DECLARE @opening_balance AS float

set @balance_c=(

select top 1 balance_after

from client_transact

where client_id=@client_id

and transdate<@transdate

order by transdate desc, id desc

)

set @balance_t=(

select top 1 client_bal_aft

from trades

where client_id=@client_id

and transdate<@transdate

order by transdate desc, id desc

)

if (COUNT(@balance_t)=0)

set @balance_t=0

if (COUNT(@balance_c)=0)

set @balance_c=0

set @opening_balance=@balance_c+@balance_t

select @opening_balance as Opening_Balance

GO