try this, using
sp_executesql[
^]
DECLARE @sqlCommand nvarchar(1000)
DECLARE @countnumber int = 0
SET @sqlCommand = 'SELECT @countnumber=count(*) from [dsnv]'
EXEC sp_executesql @sqlCommand ,N'@countnumber int out' , @countnumber out
select @countnumber ;
print @countnumber