UPDATE MyTable
SET MyDate = DATEADD(HOUR, 4, CAST(CAST(MyDate AS DATE) AS DATETIME))
Eller det här
UPDATE MyTable
SET MyDate = DATEADD(HOUR, 4, CAST(FLOOR(CAST(MyDate AS FLOAT)) AS DATETIME))
UPDATE MyTable
SET MyDate = DATEADD(HOUR, 4, CAST(CAST(MyDate AS DATE) AS DATETIME))
Eller det här
UPDATE MyTable
SET MyDate = DATEADD(HOUR, 4, CAST(FLOOR(CAST(MyDate AS FLOAT)) AS DATETIME))