Question

我已多次更改此查询但仍看到'0行受影响。一切都在SELECT语句中有效，但在UPDATE中失败。

以下是查询：

UPDATE tblVisitLog 
SET tblVisitLog.TimeOUT = (SELECT CAST(SUBSTRING(tblScheduleData.E_Time, 1,2 ) + ':' + SUBSTRING(tblScheduleData.E_Time, 3,2) + ':00.000' AS datetime)
                           FROM tblScheduleData 
                           WHERE tblVisitLog.Encounter_code = tblScheduleData.Encounter_code),
    tblVisitLog.Provider = (SELECT Provider 
                            FROM tblScheduleData s 
                            WHERE tblVisitLog.Encounter_code = s.Encounter_code), 
    tblVisitLog.recStatus = 0,
    tblVisitLog.Printed = N'N'
WHERE 
    tblVisitLog.TimeOUT IS NULL 
    AND tblVisitLog.Provider IS NULL

数据类型为：

Encounter_code (int, null)
TimeOUT (datetime, null)
Provider (nvarchar(50), null)
recStatus (smallint, not null)
Printed (nvarchar(50), null)

我正在更新的值都是NULL，我从tblScheduleData.E_Time拉出的值为varchar(4), null，格式为'1045'。

Answer 1

您的更新声明将使用此处的联接更清洁。这样的事情。

UPDATE vl 
SET TimeOUT = CAST(SUBSTRING(s.E_Time, 1,2 )+ ':' + SUBSTRING(s.E_Time, 3,2) + ':00.000' AS datetime)
    , Provider = s.Provider 
    , recStatus = 0
    , Printed = N'N'
from tblVisitLog vl
join tblScheduleData s on vl.Encounter_code = s.Encounter_code
WHERE vl.TimeOUT Is NULL 
    AND vl.Provider Is Null

Answer 2

信息非常明确'0 rows affected' 因此，尝试执行此查询，您将看到一个空结果

select * from   tblVisitLog 
WHERE TimeOUT Is NULL AND Provider Is Null

首先更改标准

SQL Server 2008中的更新获得'0行受影响'

2 个答案: