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  • 【Access】 LEFT OUTER JOIN 关联多表的查询语句

    Access 支持三表或三表以上的 JOIN 操作,但是要加括号,一层一层 JOIN 下去。

    例如:
    SELECT * FROM (aa LEFT JOIN bb ON aa.a = bb.a ) LEFT JOIN cc ONcc.a = bb.a;

    这里需要注意一个问题,在使用join语句查询时,也可以加多个条件,不过要用括号括起来,

    如:
        错误的例子:SELECT * FROM (cc LEFT JOIN aa ON aa.a=cc.a) LEFT JOIN bb ON bb.a=aa.a AND aa.b=bb.b 会报错。

    LEFT JOIN ON后面如果有多个条件时应该用括号括起来就不会出错了

        正确的写法:SELECT * FROM (aa LEFT JOIN bb ON aa.a=bb.a) LEFT JOIN cc ON(bb.a=cc.a and bb.b=cc.b)

    我的例子:
    1、SELECT * FROM URL as a LEFT OUTER JOIN MobileAfter as b  ON a.URL = b.URL

    2、SELECT * FROM (URL as a LEFT OUTER JOIN MobileAfter as b  ON a.URL= b.URL)  LEFT OUTER JOIN MobileBefore as c ONc.URL=a.URL

    3、SELECT * INTO Ttable1 FROM ((((URL as a

    LEFT OUTER JOIN MobileAfter as b  ON a.URL=b.URL)

    LEFT OUTER JOIN MobileBefore as c ON c.URL=a.URL)

    LEFT OUTER JOIN TeleCOM      as d ON d.URL=a.URL)

    LEFT OUTER JOIN UniCOM        as e ON e.URL=a.URL)

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  • 原文地址:https://www.cnblogs.com/bobbychencj/p/2276900.html
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