{"id":14286,"date":"2023-12-04T01:16:55","date_gmt":"2023-12-03T17:16:55","guid":{"rendered":"https:\/\/wx.kaifamiao.info\/?p=14286"},"modified":"2023-12-04T01:17:30","modified_gmt":"2023-12-03T17:17:30","slug":"mybatis-yi-dui-yi-yi-dui-duo-de-guan-lian-cha-xun","status":"publish","type":"post","link":"http:\/\/wx.kaifamiao.info\/index.php\/2023\/12\/04\/mybatis-yi-dui-yi-yi-dui-duo-de-guan-lian-cha-xun\/","title":{"rendered":"MyBatis \u4e00\u5bf9\u4e00\u3001\u4e00\u5bf9\u591a\u7684\u5173\u8054\u67e5\u8be2\u5982\u4f55\u914d\u7f6e\uff1f"},"content":{"rendered":"

\u5728 MyBatis \u4e2d\u8fdb\u884c\u4e00\u5bf9\u4e00\u3001\u4e00\u5bf9\u591a\u7684\u5173\u8054\u67e5\u8be2\uff0c\u53ef\u4ee5\u901a\u8fc7 association<\/code> \u548c collection<\/code> \u6807\u7b7e\u914d\u5408 resultMap<\/code> \u8fdb\u884c\u914d\u7f6e\u3002\u4e0b\u9762\u662f\u4e00\u5bf9\u4e00\u548c\u4e00\u5bf9\u591a\u5173\u8054\u67e5\u8be2\u7684\u914d\u7f6e\u793a\u4f8b\uff1a<\/p>\n

\u4e00\u5bf9\u4e00\u5173\u8054\u67e5\u8be2\uff1a<\/h3>\n

\u5047\u8bbe\u6709\u4e24\u4e2a\u8868\uff1auser<\/code> \u548c user_profile<\/code>\uff0cuser_profile<\/code> \u4e2d\u5b58\u50a8\u4e86\u7528\u6237\u7684\u989d\u5916\u4fe1\u606f\u3002<\/p>\n

    \n
  1. XML \u914d\u7f6e\uff1a<\/strong><\/li>\n<\/ol>\n
    <!-- \u5b9a\u4e49 User \u7c7b\u7684 ResultMap -->\n<resultMap id=\"userResultMap\" type=\"User\">\n  <id property=\"userId\" column=\"user_id\"\/>\n  <result property=\"userName\" column=\"user_name\"\/>\n  <!-- \u5176\u4ed6\u5c5e\u6027\u6620\u5c04 -->\n\n  <!-- \u5b9a\u4e49\u5173\u8054\u67e5\u8be2\u7684 UserProfile \u5bf9\u8c61 -->\n  <association property=\"profile\" column=\"user_id\" javaType=\"UserProfile\">\n    <id property=\"profileId\" column=\"profile_id\"\/>\n    <result property=\"profileInfo\" column=\"profile_info\"\/>\n    <!-- \u5176\u4ed6\u5c5e\u6027\u6620\u5c04 -->\n  <\/association>\n<\/resultMap>\n\n<!-- \u67e5\u8be2\u7528\u6237\u53ca\u5176\u5bf9\u5e94\u7684 UserProfile \u4fe1\u606f -->\n<select id=\"getUserWithProfile\" resultMap=\"userResultMap\">\n  SELECT u.user_id, u.user_name, p.profile_id, p.profile_info\n  FROM user u\n  LEFT JOIN user_profile p ON u.user_id = p.user_id\n  WHERE u.user_id = #{userId}\n<\/select>\n<\/code><\/pre>\n
      \n
    1. Java Mapper \u63a5\u53e3\uff1a<\/strong><\/li>\n<\/ol>\n
      public interface UserMapper {\n    User getUserWithProfile(int userId);\n}\n<\/code><\/pre>\n
      \u4e00\u5bf9\u591a\u5173\u8054\u67e5\u8be2\uff1a<\/h3>\n
      \u5047\u8bbe\u6709\u4e24\u4e2a\u8868\uff1apost<\/code> \u548c comment<\/code>\uff0c\u4e00\u4e2a\u5e16\u5b50\u5bf9\u5e94\u591a\u4e2a\u8bc4\u8bba\u3002<\/p>\n
        \n
      1. XML \u914d\u7f6e\uff1a<\/strong><\/li>\n<\/ol>\n
        <!-- \u5b9a\u4e49 Post \u7c7b\u7684 ResultMap -->\n<resultMap id=\"postResultMap\" type=\"Post\">\n  <id property=\"postId\" column=\"post_id\"\/>\n  <result property=\"postTitle\" column=\"post_title\"\/>\n  <!-- \u5176\u4ed6\u5c5e\u6027\u6620\u5c04 -->\n\n  <!-- \u5b9a\u4e49\u5173\u8054\u67e5\u8be2\u7684 Comment \u96c6\u5408 -->\n  <collection property=\"comments\" ofType=\"Comment\">\n    <id property=\"commentId\" column=\"comment_id\"\/>\n    <result property=\"commentContent\" column=\"comment_content\"\/>\n    <!-- \u5176\u4ed6\u5c5e\u6027\u6620\u5c04 -->\n  <\/collection>\n<\/resultMap>\n\n<!-- \u67e5\u8be2\u5e16\u5b50\u53ca\u5176\u5bf9\u5e94\u7684\u8bc4\u8bba\u4fe1\u606f -->\n<select id=\"getPostWithComments\" resultMap=\"postResultMap\">\n  SELECT p.post_id, p.post_title, c.comment_id, c.comment_content\n  FROM post p\n  LEFT JOIN comment c ON p.post_id = c.post_id\n  WHERE p.post_id = #{postId}\n<\/select>\n<\/code><\/pre>\n
          \n
        1. Java Mapper \u63a5\u53e3\uff1a<\/strong><\/li>\n<\/ol>\n
          public interface PostMapper {\n    Post getPostWithComments(int postId);\n}\n<\/code><\/pre>\n
          \u4ee5\u4e0a\u914d\u7f6e\u901a\u8fc7 association<\/code> \u548c collection<\/code> \u6807\u7b7e\uff0c\u5728 resultMap<\/code> \u4e2d\u5b9a\u4e49\u4e86\u4e00\u5bf9\u4e00\u548c\u4e00\u5bf9\u591a\u7684\u5173\u8054\u5173\u7cfb\uff0c\u5b9e\u73b0\u4e86\u67e5\u8be2\u7ed3\u679c\u7684\u6620\u5c04\u3002\u5728 SQL \u67e5\u8be2\u8bed\u53e5\u4e2d\uff0c\u901a\u8fc7 LEFT JOIN<\/code> \u7b49\u65b9\u5f0f\u5173\u8054\u67e5\u8be2\u76f8\u5173\u8868\u7684\u6570\u636e\uff0c\u5e76\u4f7f\u7528 resultMap<\/code> \u5c06\u7ed3\u679c\u6620\u5c04\u5230 Java \u5bf9\u8c61\u4e2d\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
          \u5728 MyBatis \u4e2d\u8fdb\u884c\u4e00\u5bf9\u4e00\u3001\u4e00\u5bf9\u591a\u7684\u5173\u8054\u67e5\u8be2\uff0c\u53ef\u4ee5\u901a\u8fc7 association \u548c collection […]<\/p>\n","protected":false},"author":11,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[113],"tags":[],"class_list":["post-14286","post","type-post","status-publish","format-standard","hentry","category-mybatis"],"_links":{"self":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/14286","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/users\/11"}],"replies":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/comments?post=14286"}],"version-history":[{"count":1,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/14286\/revisions"}],"predecessor-version":[{"id":14287,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/14286\/revisions\/14287"}],"wp:attachment":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/media?parent=14286"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/categories?post=14286"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/tags?post=14286"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}