{"id":151446,"date":"2020-08-30T06:33:46","date_gmt":"2020-08-29T22:33:46","guid":{"rendered":"http:\/\/4563.org\/?p=151446"},"modified":"2020-08-30T06:33:46","modified_gmt":"2020-08-29T22:33:46","slug":"%e8%af%b7%e6%95%99-left-join-%e5%8f%b3%e8%a1%a8%e5%90%8e%ef%bc%8c%e5%8f%aa%e8%bf%94%e5%9b%9e-%e5%9c%a8-leftjoin-%e7%9a%84%e7%bb%93%e6%9e%9c%e9%87%8c%ef%bc%8c%e8%bf%94%e5%9b%9e%e5%8f%b3%e8%a1%a8","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=151446","title":{"rendered":"\u8bf7\u6559 left join \u53f3\u8868\u540e\uff0c\u53ea\u8fd4\u56de \u5728 leftjoin \u7684\u7ed3\u679c\u91cc\uff0c\u8fd4\u56de\u53f3\u8868\u4e2d OrderNo \u6700\u5927\u7684\u90a3\u4e00\u6761"},"content":{"rendered":"
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\u8bf7\u6559 left join \u53f3\u8868\u540e\uff0c\u53ea\u8fd4\u56de \u5728 leftjoin \u7684\u7ed3\u679c\u91cc\uff0c\u8fd4\u56de\u53f3\u8868\u4e2d OrderNo \u6700\u5927\u7684\u90a3\u4e00\u6761 <\/h1>\n

<\/p>\n

\n
\u8cc7\u6df1\u5927\u4f6c : rqxiao <\/span> <\/i> 9<\/span> <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n
https:\/\/www.w3school.com.cn\/sql\/sql_join_left.asp<\/p>\n

\u60f3\u8981 \u7ed3\u679c<\/p>\n

Adams John 24562<\/p>\n

Carter Thomas 77895<\/p>\n

Bush George <\/div>\n

\u5927\u4f6c\u6709\u8a71\u8aaa<\/b> (12<\/span>) <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n
    \n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : taogen <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    select \u2026 from A join B \u2026 order by orderNo desc limit 1 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : zhenglee <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    SELECT Persons.LastName, Persons.FirstName, Orders.OrderNo
    FROM Persons
    LEFT JOIN Orders
    ON Persons.Id_P=Orders.Id_P
    where Orders.OrderNo in
    (select max(OrderNo) from Orders group by ID_P)
    ORDER BY Persons.LastName <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : taogen <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @zhenglee group by \u548c \u805a\u5408\u51fd\u6570\uff0c\u8981\u4f7f\u7528\u76f8\u540c\u5b57\u6bb5 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : zhenglee <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @taogen \u6ca1\u6709\u8fd9\u4e48\u4e00\u8bf4\uff0c\u5b9e\u8df5\u51fa\u771f\u77e5\u3002 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : taogen <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @zhenglee \u4e0d\u597d\u610f\u601d\uff0c\u6211\u8bb0\u9519\u4e86\u3002 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : CRVV <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u53ea\u53d6\u6700\u5927\u7684\u4e00\u6761\u53ef\u4ee5\u4e0d\u7528 JOIN<\/p>\n

    SELECT Persons.LastName, Persons.FirstName,
    (SELECT max(OrderNo) FROM Orders WHERE Orders.Id_P = Persons.Id_P) AS OrderNo
    FROM Persons;<\/p>\n

    \u5982\u679c\u8981\u53d6\u6700\u5927\u7684\u4e24\u6761\uff0c\u5c31\u5f97\u7528 2 \u7684\u65b9\u6cd5<\/p>\n

    \u4e5f\u53ef\u4ee5\u7528 window function\uff0cMySQL 8 \u652f\u6301\u4e86 <\/p><\/div>\n<\/p><\/div>\n<\/li>\n

  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : weizhen199 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u7b49\u7b49\uff0c\u6211\u662f\u4e0d\u662f\u7406\u89e3\u9519\u4e86\u4ec0\u4e48
    \u4f60\u8981\u8fd4\u56de\u53f3\u8868\u91cc order by NO \u6700\u5927\u7684\u90a3\u6761\uff0c\u90a3\u8fd8\u8981 left join \u5e72\u9524\u5b50 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : zhangysh1995 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u7528\u53f3\u8868 EXISTS \u6d4b\u8bd5\u76f8\u7b49\u7684\u503c\u5728\u5de6\u8868\u662f\u5426\u5b58\u5728\uff0c\u4e24\u5f20\u8868 Id_P \u52a0\u7d22\u5f15<\/p>\n

    SELECT max(OrderNo)
    FROM (
    SELECT Orders.Id, OrderNo
    FROM Orders
    WHERE EXISTS (
    SELECT *
    FROM Persons
    WHERE Orders.ID_P = Persons.Id_P)
    ) t;<\/p>\n

    MySQL \u4e2d EXISTS \u90e8\u5206 SELECT * \u4e0d\u4f1a\u5b9e\u9645\u53d6\u6570\u636e\uff0c\u5bf9\u901f\u5ea6\u6ca1\u5f71\u54cd\u3002 <\/p><\/div>\n<\/p><\/div>\n<\/li>\n

  • \n
    \n
    \n
    \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : rqxiao <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    SELECT
    a.*,
    b.*
    FROM
    lefta a
    LEFT JOIN ( SELECT max( id ), a_id FROM leftb GROUP BY a_id ) b ON a.id = b.a_id
    \u5dee\u4e0d\u591a\u8fd9\u6837\u5b50\u4e5f\u884c\u4e86 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : alex321 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u4e4b\u524d\u9047\u5230\u8fc7\u8fd9\u4e2a\u95ee\u9898\uff0c\u7275\u6d89\u5230 4 \u5f20\u8868\u7684\u6570\u636e\uff0c\u5176\u4e2d 1 \u5f20\u8868\u9700\u8981\u6309\u7167\u9898\u4e3b\u7684\u60c5\u51b5\u8bfb\u53d6\u3002\u5f53\u65f6\u4e00\u65f6\u6ca1\u60f3\u5230\u5565\u529e\u6cd5\uff0c\u5c31\u4f7f\u7528\u4e86\u5206\u89e3\u6210\u4e24\u6b65\u7684\u65b9\u5f0f\u5904\u7406\u3002
    \u521a\u624d\u4f7f\u7528 #6 \u7684\u65b9\u5f0f\uff0c\u91cd\u65b0\u5c1d\u8bd5\u4e86\u4e0b\uff0c\u8bc1\u5b9e\u662f\u53ef\u884c\u7684\uff0c\u4f46\u8bf7\u6ce8\u610f\u76f4\u63a5\u67e5\u8be2\u65f6\u7684\u6027\u80fd\u635f\u8017\u3002\u6211\u8fd9\u91cc\u5b9e\u9645\u6d4b\u8bd5\u7684\u7ed3\u679c\uff0c4 \u5f20\u8868\u603b\u548c\u5dee\u4e0d\u591a 1000 \u6761\u6570\u636e\uff0c\u5206\u89e3\u65b9\u5f0f\u7684\u9875\u9762\u603b\u6267\u884c\u65f6\u95f4\u662f 0.0880s\uff0c\u65b0\u65b9\u5f0f\u7684\u9875\u9762\u603b\u6267\u884c\u65f6\u95f4\u662f 0.1110s \u3002\u591a\u6b21\u6267\u884c\u65f6\u95f4\u76f8\u5bf9\u7a33\u5b9a\u3002
    \u57fa\u4e8e\u73af\u5883\uff1aWindows 7 64Bit + IIS 7.5 + PHP 5.6.40 32Bit \uff08 FastCGI \uff09 + MariaDB 5.5.66 \uff0c\u5404\u8868\u5747\u662f MyISAM \u3001utf8_general_ci \u548c\u81ea\u589e\u4e3b\u952e\uff0c\u5e76\u8bbe\u7f6e\u4e86\u7d22\u5f15\uff0c\u6ca1\u6709\u4f7f\u7528\u7f13\u5b58\u3002 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : xhq <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u6211\u4e4b\u524d\u7528\u5b50\u67e5\u8be2\u597d\u50cf\u6027\u80fd\u6709\u70b9\u95ee\u9898\uff0c\u627e\u5230\u4e2a\u53ea\u7528\u5916\u8fde\u63a5\u7684\u529e\u6cd5\uff0c\u4e3b\u8bd5\u8bd5
    https:\/\/stackoverflow.com\/a\/584442 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : JJstyle <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @zhenglee \u6709\u70b9\u95ee\u9898\uff0cBush George \u6ca1\u6709\u8ba2\u5355\uff0c\u88ab\u4f60\u8fc7\u6ee4\u6389\u4e86\uff0c\u4f46\u4e3b\u8fd8\u60f3\u5728\u7ed3\u679c\u4e2d\u4fdd\u7559\u4ed6(\u6211\u53ef\u80fd\u6709\u70b9\u5439\u6bdb\u6c42\u75b5\u4e86) <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n","protected":false},"excerpt":{"rendered":"

    \u8bf7\u6559 left join \u53f3\u8868\u540e\uff0c…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[],"tags":[],"_links":{"self":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/151446"}],"collection":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=151446"}],"version-history":[{"count":0,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/151446\/revisions"}],"wp:attachment":[{"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=151446"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=151446"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=151446"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}