Question

我对sql很新，我正在努力创建一个查询。我有两张桌子：

字符

或CharacterId
姓名
名字
性别

夫妻

coupleID
femaleID
maleID

现在我试图把它拼凑起来：

femaleFName
femaleLName
maleFName
maleLName

我试过了：

var dbCofing = {
    user: 'USER',
    password: 'PASS',
    server: '53.165.137.28\\NAME,94273',
    database: 'DATABASE'
}

但现在我正在努力与第二次加入。

Answer 1

您所要做的就是第二次加入桌子。为此，您必须提供别名，以便不会混淆表格。

SELECT 
cf.firstname AS femaleFName, cf.lastname AS femaleLName,
mf.firstname AS maleFName, mf.lastname AS maleLName
FROM Couple 
INNER JOIN Character AS cf ON cf.characterID = Couple.femaleID
INNER JOIN Character AS mf ON mf.characterID = Couple.maleID

关键字AS不是强制性的，可以省略。

Answer 2

添加另一个JOIN，如下所示。这里c是区分第二个连接的表别名

SELECT character.firstname AS femaleFName, character.lastname AS femaleLName
FROM character INNER JOIN Couple ON Character.characterID = Couple.femaleID
INNER JOIN Couple c ON Character.characterID = c.maleID

Answer 3

您需要使用自我加入来获得所需的结果。使用以下查询可以根据需要获得结果。

WARNINGS:
?: (urls.W002) Your URL pattern '^/(?P<slug>[\w-]+)/form/$'
[name='person_form'] has a regex beginning with a '/'. Remove this 
slash as it is unnecessary. If this pattern is targeted in an 
include(), ensure the include() pattern has a trailing '/'.

我希望这对你有所帮助。

谢谢！

SQL加入初学者

3 个答案: