Question

为什么当我输入代码时：

A = 0
B = 0

while A<10 or B<5:
    A+=1
    B+=1
    print(A)
    print(B)

当B = 5时循环不会停止；而是继续将A和B都加1，直到A = 10，然后停止。当我交换订单时，会发生相同的事情，例如：

while B<5 or A<10:

当我用'and'替换'or'时，代码在B = 5时停止，这正是我想要的方式。我对“或”和“与”的实际工作方式感到困惑。

Answer 1

类似于英语：

任何

or

True给出True。

所有

and

True给出True。

Answer 2

-- Create a Temporary table for keep Maid_Id and AppointmentDateTime CREATE TABLE #TEMP ( Maid_Id INT, AppointmentDateTime DATETIME ) -- Select all AppointmentDateTime are present in Appointment DECLARE db_cursor CURSOR FOR SELECT distinct Appointment.AppointmentDateTime FROM Appointment; -- Iterate them to insert them into the temporary table DECLARE @date datetime; OPEN db_cursor; FETCH NEXT FROM db_cursor INTO @date; WHILE @@FETCH_STATUS = 0 BEGIN INSERT INTO #TEMP (Maid_Id, AppointmentDateTime) SELECT M.Maid_Id, @date FROM Maid M WHERE M.Maid_Id NOT IN ( SELECT a.Maid_Id FROM Appointment a WHERE A.AppointmentDateTime = @date ) FETCH NEXT FROM db_cursor INTO @date; END; CLOSE db_cursor; DEALLOCATE db_cursor; -- Create another temporary table to keep all the dates we need DECLARE @MinDate DATE = '2019-05-10', @MaxDate DATE = '2019-07-24'; CREATE TABLE #DATES ( [DATE] DATETIME ) -- Create a range of dates that we need and insert them in the temporary table. It can cover a wide range of dates like 2000-01-01 to Now INSERT INTO #DATES SELECT TOP (DATEDIFF(DAY, @MinDate, @MaxDate) + 1) Date = DATEADD(DAY, ROW_NUMBER() OVER(ORDER BY A.OBJECT_ID) - 1, @MinDate) FROM SYS.ALL_OBJECTS A CROSS JOIN SYS.ALL_OBJECTS B; -- Union all the data SELECT M.Maid_Id, M.Maid_Name, CONVERT(NVARCHAR(10), T.AppointmentDateTime, 120) [date] FROM #TEMP T INNER JOIN Maid M ON T.Maid_Id = M.Maid_Id UNION SELECT null, 'All People Are Free', CONVERT(NVARCHAR(10), [DATE], 120) FROM #DATES ORDER BY [date] DROP TABLE #TEMP DROP TABLE #DATES <10和B <A表示当5小于A AND {{1} }小于10（检查两个条件），或者换句话说，只有当B的值大于或等于5时，它才会停止 OR A的值大于或等于10（两个值中的任何一个）。

对于B <10或B <5，如果A的值小于5，则循环将继续进行 OR A的值小于10（两个值中的任何一个）。也就是说，如果B和5仍将继续循环，因为A = 10仍满足条件。仅当B = 2的值大于或等于10 并且 B的值大于或等于A时，循环才会终止（两个必须为真）。

Python中的while循环和逻辑运算符-它如何工作？

2 个答案: