SET DATEFIRST CURSOR WHILE LOOP 错误 - 设置选项已更改

Question

我的光标循环出现了非常奇怪的行为，这就是我得到的结果；

DECLARE @StartDate AS DATE
DECLARE @ID INT
DECLARE CursorTest CURSOR FOR  
SELECT ID FROM tblSomething

OPEN Schedule
FETCH NEXT FROM CursorTest INTO @ID

WHILE @@FETCH_STATUS = 0
    BEGIN
        SELECT @StartDate = StartDate FROM tblAnother WHERE ID = @ID
        SELECT @StartDate --12/06/2018
        -- NOW WE MOD IT
        SET DATEFIRST 6 -- WE START ON SATURDAY 1
        SET @StartDate = DATEPART(dw,@StartDate)
        SELECT @StartDate -- ANSWER IS 4
        FETCH NEXT FROM CursorTest INTO @ID
    END

CLOSE CursorTest
DEALLOCATE CursorTest

现在，如果我运行到达 CURSOR 的第二行，它将崩溃并显示；

Could not complete cursor operation because the set options have changed since the cursor was declared.

现在如果我注释掉;

--SET DATEFIRST 6

错误消失了，所以我认为 SET DATEFIRST 正在修改导致错误的数据库。

是否可以使用类似的东西解决这个问题；

SET @StartDate = DATEPART(dw,@StartDate,DATEFIRST 6)

类似的东西。

Answer 1

你可以移动 SET:

DECLARE @StartDate AS DATE
DECLARE @ID INT
DECLARE CursorTest CURSOR FOR  
SELECT ID FROM tblSomething

SET DATEFIRST 6 -- WE START ON SATURDAY 1

OPEN Schedule
FETCH NEXT FROM CursorTest INTO @ID

WHILE @@FETCH_STATUS = 0
    BEGIN
        SELECT @StartDate = StartDate FROM tblAnother WHERE ID = @ID
        SELECT @StartDate --12/06/2018
        -- NOW WE MOD IT

        SET @StartDate = DATEPART(dw,@StartDate)
        SELECT @StartDate -- ANSWER IS 4
        FETCH NEXT FROM CursorTest INTO @ID
    END

CLOSE CursorTest
DEALLOCATE CursorTest

Answer 2

我修好了；

SET DATEFIRST 6 -- outside CURSOR LOOP;
WHILE @@FETCH_STATUS = 0
    BEGIN
        SET @StartWeek = DATEPART(wk,@StartDate) -- CORRECT BY DATEFIRST 6
        SET @StartDay = (DATEPART(dw,@StartDate) + @@DATEFIRST - 1 - 1) % 7 + 1 -- MONDAY 1
    END

SET DATEFIRST CURSOR WHILE LOOP 错误 - 设置选项已更改

SET DATEFIRST CURSOR WHILE LOOP Error - set options have changed

sql-server

date

while-loop

cursor