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  • 数据库如何连接三个表

    相对最优:

    SELECT ASSETCHANGEAPPLYINFO.*,ASSETCHANGEINFO.OPERATION

                   FROM

                        ASSETCHANGEINFO_ASSETCHANGEAPPLYINFO

                        INNER JOIN ASSETCHANGEAPPLYINFO ON ASSETCHANGEINFO_ASSETCHANGEAPPLYINFO.ASSET_CHANGE_APPLYINFO_ID = ASSETCHANGEAPPLYINFO.ID

                       LEFT JOIN ASSETCHANGEINFO ON ASSETCHANGEINFO_ASSETCHANGEAPPLYINFO.ASSET_CHANGEINFO_ID=ASSETCHANGEINFO.ID

     另外的方法:

    SELECT a.*, ASSETCHANGEINFO.OPERATION

                   FROM (

                        SELECT * FROM   ASSETCHANGEINFO_ASSETCHANGEAPPLYINFO

                        INNER JOIN ASSETCHANGEAPPLYINFO ON ASSETCHANGEINFO_ASSETCHANGEAPPLYINFO.ASSET_CHANGE_APPLYINFO_ID = ASSETCHANGEAPPLYINFO.ID) AS a

                        LEFT JOIN ASSETCHANGEINFO ON a.ASSET_CHANGEINFO_ID=ASSETCHANGEINFO.ID

     SELECT        ASSETCHANGEAPPLYINFO.*,ASSETCHANGEINFO.OPERATION

                   FROM

                        ASSETCHANGEINFO_ASSETCHANGEAPPLYINFO,ASSETCHANGEAPPLYINFO,ASSETCHANGEINFO

                       WHERE ASSETCHANGEINFO_ASSETCHANGEAPPLYINFO.ASSET_CHANGE_APPLYINFO_ID = ASSETCHANGEAPPLYINFO.ID

                       AND ASSETCHANGEINFO_ASSETCHANGEAPPLYINFO.ASSET_CHANGEINFO_ID=ASSETCHANGEINFO.ID

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  • 原文地址:https://www.cnblogs.com/guozhiguoli/p/3255354.html
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