{"id":18655,"date":"2024-03-15T17:23:36","date_gmt":"2024-03-15T17:23:36","guid":{"rendered":"https:\/\/www.silicloud.com\/blog\/how-to-handle-the-issue-of-mybatis-one-to-many-queries\/"},"modified":"2024-03-21T13:49:43","modified_gmt":"2024-03-21T13:49:43","slug":"how-to-handle-the-issue-of-mybatis-one-to-many-queries","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/blog\/how-to-handle-the-issue-of-mybatis-one-to-many-queries\/","title":{"rendered":"How to handle the issue of Mybatis one-to-many queries"},"content":{"rendered":"

Mybatis offers great support for handling one-to-many query issues. Here are some methods for dealing with one-to-many query problems.<\/p>\n

    \n
  1. group of items or objects gathered together<\/li>\n<\/ol>\n
    <resultMap<\/span> id<\/span>=\"userMap\"<\/span> type<\/span>=\"User\"<\/span>><\/span>\r\n  <id<\/span> column<\/span>=\"id\"<\/span> property<\/span>=\"id\"<\/span> \/><\/span>\r\n  <result<\/span> column<\/span>=\"name\"<\/span> property<\/span>=\"name\"<\/span> \/><\/span>\r\n  <collection<\/span> property<\/span>=\"orders\"<\/span> ofType<\/span>=\"Order\"<\/span>><\/span>\r\n    <id<\/span> column<\/span>=\"order_id\"<\/span> property<\/span>=\"id\"<\/span> \/><\/span>\r\n    <result<\/span> column<\/span>=\"order_name\"<\/span> property<\/span>=\"name\"<\/span> \/><\/span>\r\n  <\/collection<\/span>><\/span>\r\n<\/resultMap<\/span>><\/span>\r\n\r\n<select<\/span> id<\/span>=\"getUserWithOrders\"<\/span> resultMap<\/span>=\"userMap\"<\/span>><\/span>\r\n  SELECT u.id, u.name, o.id as order_id, o.name as order_name\r\n  FROM user u\r\n  LEFT JOIN order o ON u.id = o.user_id\r\n  WHERE u.id = #{id}\r\n<\/select<\/span>><\/span>\r\n<\/code><\/pre>\n
      \n
    1. union<\/li>\n
    2. Assortment<\/li>\n<\/ol>\n
      <resultMap<\/span> id<\/span>=\"userMap\"<\/span> type<\/span>=\"User\"<\/span>><\/span>\r\n  <id<\/span> column<\/span>=\"id\"<\/span> property<\/span>=\"id\"<\/span> \/><\/span>\r\n  <result<\/span> column<\/span>=\"name\"<\/span> property<\/span>=\"name\"<\/span> \/><\/span>\r\n  <association<\/span> property<\/span>=\"department\"<\/span> javaType<\/span>=\"Department\"<\/span>><\/span>\r\n    <id<\/span> column<\/span>=\"department_id\"<\/span> property<\/span>=\"id\"<\/span> \/><\/span>\r\n    <result<\/span> column<\/span>=\"department_name\"<\/span> property<\/span>=\"name\"<\/span> \/><\/span>\r\n    <collection<\/span> property<\/span>=\"employees\"<\/span> ofType<\/span>=\"Employee\"<\/span>><\/span>\r\n      <id<\/span> column<\/span>=\"employee_id\"<\/span> property<\/span>=\"id\"<\/span> \/><\/span>\r\n      <result<\/span> column<\/span>=\"employee_name\"<\/span> property<\/span>=\"name\"<\/span> \/><\/span>\r\n    <\/collection<\/span>><\/span>\r\n  <\/association<\/span>><\/span>\r\n<\/resultMap<\/span>><\/span>\r\n\r\n<select<\/span> id<\/span>=\"getUserWithDepartmentAndEmployees\"<\/span> resultMap<\/span>=\"userMap\"<\/span>><\/span>\r\n  SELECT u.id, u.name, d.id as department_id, d.name as department_name, e.id as employee_id, e.name as employee_name\r\n  FROM user u\r\n  LEFT JOIN department d ON u.department_id = d.id\r\n  LEFT JOIN employee e ON d.id = e.department_id\r\n  WHERE u.id = #{id}\r\n<\/select<\/span>><\/span>\r\n<\/code><\/pre>\n
        \n
      1. Using nested queries is a way to handle retrieving multiple related child objects while querying the main object. This approach is suitable for cases where the one-to-many relationship is relatively straightforward.<\/li>\n<\/ol>\n
        <select<\/span> id<\/span>=\"getUserWithOrders\"<\/span> resultType<\/span>=\"User\"<\/span>><\/span>\r\n  SELECT u.id, u.name, (SELECT o.id, o.name FROM order o WHERE o.user_id = u.id) as orders\r\n  FROM user u\r\n  WHERE u.id = #{id}\r\n<\/select<\/span>><\/span>\r\n<\/code><\/pre>\n
        These methods can be chosen based on specific business needs, taking into account the complexity of relationships and query performance.<\/p>\n","protected":false},"excerpt":{"rendered":"
        Mybatis offers great support for handling one-to-many query issues. Here are some methods for dealing with one-to-many query problems. group of items or objects gathered together <resultMap id=”userMap” type=”User”> <id column=”id” property=”id” \/> <result column=”name” property=”name” \/> <collection property=”orders” ofType=”Order”> <id column=”order_id” property=”id” \/> <result column=”order_name” property=”name” \/> <\/collection> <\/resultMap> <select id=”getUserWithOrders” resultMap=”userMap”> SELECT u.id, […]<\/p>\n","protected":false},"author":8,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_import_markdown_pro_load_document_selector":0,"_import_markdown_pro_submit_text_textarea":"","footnotes":""},"categories":[1],"tags":[],"class_list":["post-18655","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"yoast_head":"\nHow to handle the issue of Mybatis one-to-many queries - Blog - Silicon Cloud<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.silicloud.com\/blog\/how-to-handle-the-issue-of-mybatis-one-to-many-queries\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"How to handle the issue of Mybatis one-to-many queries\" \/>\n<meta property=\"og:description\" content=\"Mybatis offers great support for handling one-to-many query issues. Here are some methods for dealing with one-to-many query problems. group of items or objects gathered together <resultMap id="userMap" type="User"> <id column="id" property="id" \/> <result column="name" property="name" \/> <collection property="orders" ofType="Order"> <id column="order_id" property="id" \/> <result column="order_name" property="name" \/> <\/collection> <\/resultMap> <select id="getUserWithOrders" resultMap="userMap"> SELECT u.id, […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.silicloud.com\/blog\/how-to-handle-the-issue-of-mybatis-one-to-many-queries\/\" \/>\n<meta property=\"og:site_name\" content=\"Blog - Silicon Cloud\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/SiliCloudGlobal\/\" \/>\n<meta property=\"article:published_time\" content=\"2024-03-15T17:23:36+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2024-03-21T13:49:43+00:00\" \/>\n<meta name=\"author\" content=\"William Carter\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@SiliCloudGlobal\" \/>\n<meta name=\"twitter:site\" content=\"@SiliCloudGlobal\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"William Carter\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/how-to-handle-the-issue-of-mybatis-one-to-many-queries\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/how-to-handle-the-issue-of-mybatis-one-to-many-queries\/\"},\"author\":{\"name\":\"William Carter\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/#\/schema\/person\/f697031891aacefc4b681d139781d3c0\"},\"headline\":\"How to handle the issue of Mybatis one-to-many queries\",\"datePublished\":\"2024-03-15T17:23:36+00:00\",\"dateModified\":\"2024-03-21T13:49:43+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/how-to-handle-the-issue-of-mybatis-one-to-many-queries\/\"},\"wordCount\":88,\"commentCount\":0,\"publisher\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/#organization\"},\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/how-to-handle-the-issue-of-mybatis-one-to-many-queries\/\",\"url\":\"https:\/\/www.silicloud.com\/blog\/how-to-handle-the-issue-of-mybatis-one-to-many-queries\/\",\"name\":\"How to handle the issue of Mybatis one-to-many queries - 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