Question

我有3张桌子：

Visitor table
VisitorId (pk)
Name
Phone


Country table
CountryId (pk)
Name
Code

Travels table
TravelId (pk)
CountryId (fk)
VisitorId (fk)
IsVisited (bool)

我希望该foreach国家能够在Travels表格中为CountryId创建包含VisitorId，false和IsVisited的其他内容。

更新

INSERT INTO Travels (CountryId, VisitorID, IsVisisted)
SELECT Visitor.VisitorId, Country.CountryId, 1 FROM Visitor, Country

Answer 1

你应该写为：

-- STEP2: Insert records:
INSERT INTO @Travels 
SELECT CountryId,VisitorId,0 FROM -- 0 = false for IsVisited
(
-- STEP1: first create a combination for all visitor Id and country Id 
-- and get all the combinations which are not there in existing Travels table
SELECT C.CountryId,V.VisitorId
FROM @Country C
CROSS JOIN @Visitor V
EXCEPT
SELECT CountryId,VisitorId
FROM @Travels
) AS T

否则，如果您想在Country和Visitor中为每个组合创建一个条目，请写为：

-- STEP2: Insert records:
INSERT INTO @Travels 
SELECT  CountryId,VisitorId,0 FROM 
(
-- STEP1: first create a combination for all visitor Id and country Id 
SELECT C.CountryId,V.VisitorId
FROM @Country C
CROSS JOIN @Visitor V
) AS T

SELECT * FROM @Travels

Sql从多个表中选择

1 个答案: