Question

    CREATE TABLE [dbo].[Country](
        [Id] [int] NOT NULL,
        [name] [varchar](50) NULL)

    CREATE TABLE [dbo].[State](
        [Id] [int] NOT NULL,
        [name] [varchar](50) NULL,
             [CountryId] [int] NULL references Country(Id))

    CREATE TABLE [dbo].[City](
        [Id] [int] NOT NULL,
        [name] [varchar](50) NULL,
             [StateId] [int] NULL references State(Id))

Value in table

国家

-------
1 USA
2 UK

国家

-----
1 NY 1
2 NSW NULL

市

-----
1 Sydney 2
2 Mumbai NULL
3 Delhi 1

现在我想要City.Name，State.Name，Country.Name列表也是NULL值。

例如悉尼新南威尔士州德里纽约美国避免重复记录

我尝试了这个查询，但其中有一些错误：

SELECT        Country.name, City.Name AS Expr1, State.Name AS Expr2
FROM            City CROSS JOIN
                         State CROSS JOIN
                         Country
WHERE        (City.StateId IN
                             (SELECT        StateId
                               FROM            City AS City_1)) OR
                         (State.CountryId IN
                             (SELECT        CountryId
                               FROM            State AS State_1))

Answer 1

SELECT        C2.name, C.Name AS Expr1, S.Name AS Expr2
FROM            City c 
LEFT OUTER  JOIN State s ON c.stateid = s.id
LEFT OUTER  JOIN Country c2 on s.countryId = c2.id

交叉连接Sql查询

1 个答案: