DECLARE @sm DATETIME;
SET @sm = DATEADD(DAY, 1-DAY(GETDATE()), DATEDIFF(DAY, 0, GETDATE()));
SELECT columns
FROM dbo.foo
WHERE datetime_column >= @sm;
DECLARE @sm DATETIME;
SET @sm = DATEADD(DAY, 1-DAY(GETDATE()), DATEDIFF(DAY, 0, GETDATE()));
SELECT columns
FROM dbo.foo
WHERE datetime_column >= @sm;