{"id":31519,"date":"2023-05-24T11:44:54","date_gmt":"2023-05-24T03:44:54","guid":{"rendered":"https:\/\/docs.pingcode.com\/?p=31519"},"modified":"2023-07-31T00:08:26","modified_gmt":"2023-07-30T16:08:26","slug":"mybatis%e4%b8%ad%e5%8f%82%e6%95%b0%e6%98%aflist%e7%b1%bb%e5%9e%8b%e6%97%b6%e6%80%8e%e4%b9%88%e5%a4%84%e7%90%86","status":"publish","type":"post","link":"https:\/\/docs.pingcode.com\/ask\/31519.html","title":{"rendered":"MyBatis\u4e2d\u53c2\u6570\u662fList\u7c7b\u578b\u65f6\u600e\u4e48\u5904\u7406"},"content":{"rendered":"
\n

MyBatis\u4e2d\u53c2\u6570\u662fList\u7c7b\u578b\u65f6\u53ef\u4ee5\u7528foreach\u3002 foreach\u7684\u4e3b\u8981\u7528\u5728\u6784\u5efain\u6761\u4ef6\u4e2d\uff0c\u5b83\u53ef\u4ee5\u5728SQL\u8bed\u53e5\u4e2d\u8fdb\u884c\u8fed\u4ee3\u4e00\u4e2a\u96c6\u5408\u3002foreach\u5143\u7d20\u7684\u5c5e\u6027\u4e3b\u8981\u6709item\uff0cindex\uff0ccollection\uff0copen\uff0cseparator\uff0cclose\u3002item\u8868\u793a\u96c6\u5408\u4e2d\u6bcf\u4e00\u4e2a\u5143\u7d20\u8fdb\u884c\u8fed\u4ee3\u65f6\u7684\u522b\u540d\uff0cindex\u6307\u5b9a\u4e00\u4e2a\u540d\u5b57\uff0c\u7528\u4e8e\u8868\u793a\u5728\u8fed\u4ee3\u8fc7\u7a0b\u4e2d\u3002<\/p>\n<\/blockquote>\n

\n
\"\"<\/figure>\n<\/div>\n

\u4e00\u3001MyBatis\u4e2d\u53c2\u6570\u662fList\u7c7b\u578b\u65f6\u600e\u4e48\u5904\u7406<\/strong><\/h2>\n

MyBatis\u4e2d\u53c2\u6570\u662fList\u7c7b\u578b\u65f6\u53ef\u4ee5\u7528foreach\u3002 foreach\u7684\u4e3b\u8981\u7528\u5728\u6784\u5efain\u6761\u4ef6\u4e2d\uff0c\u5b83\u53ef\u4ee5\u5728SQL\u8bed\u53e5\u4e2d\u8fdb\u884c\u8fed\u4ee3\u4e00\u4e2a\u96c6\u5408\u3002foreach\u5143\u7d20\u7684\u5c5e\u6027\u4e3b\u8981\u6709item\uff0cindex\uff0ccollection\uff0copen\uff0cseparator\uff0cclose\u3002item\u8868\u793a\u96c6\u5408\u4e2d\u6bcf\u4e00\u4e2a\u5143\u7d20\u8fdb\u884c\u8fed\u4ee3\u65f6\u7684\u522b\u540d\uff0cindex\u6307\u5b9a\u4e00\u4e2a\u540d\u5b57\uff0c\u7528\u4e8e\u8868\u793a\u5728\u8fed\u4ee3\u8fc7\u7a0b\u4e2d\u3002<\/p>\n

1. <\/strong>\u573a\u666f\u590d\u73b0<\/strong><\/h3>\n

\u9996\u5148\u6709\u5982\u4e0b\u4e00\u5f20\u8868\uff1a<\/p>\n

MySQL [test]> select * from t_entry_resource;<\/p>\n

+\u2014-+\u2014\u2014\u2014\u2014-+\u2014\u2014+\u2014\u2014\u2014-+\u2014\u2014\u2013+\u2014\u2014\u2013+\u2014\u2014\u2014\u2014\u2014\u2014\u2014+<\/p>\n

| id | resource_id | type | title\u00a0\u00a0\u00a0 | banner | icon\u00a0 | add_date\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |<\/p>\n

+\u2014-+\u2014\u2014\u2014\u2014-+\u2014\u2014+\u2014\u2014\u2014-+\u2014\u2014\u2013+\u2014\u2014\u2013+\u2014\u2014\u2014\u2014\u2014\u2014\u2014+<\/p>\n

| 11 |\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 6\u00a0 | 14\u00a0\u00a0 | \u5206\u7c7b\u00a0\u00a0\u00a0\u00a0 | 1.jpg\u00a0 | 2.jpg\u00a0 | 2017-11-17 11:22:30 |<\/p>\n

| 12 |\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 3\u00a0 | 1\u00a0\u00a0\u00a0 | \u6d4b\u8bd512\u00a0\u00a0 | 3.jpg\u00a0 | 4.jpg\u00a0 | 2017-11-17 11:22:30 |<\/p>\n

| 13 |\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 653\u00a0 | 1\u00a0\u00a0\u00a0 | \u6d4b\u8bd534\u00a0\u00a0 | 5.jpg\u00a0 | 6.jpg\u00a0 | 2017-11-20 02:32:26 |<\/p>\n

| 14 |\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1\u00a0 | 1\u00a0\u00a0\u00a0 | \u6d4b\u8bd55\u00a0\u00a0\u00a0 | 7.jpg\u00a0 | 8.jpg\u00a0 | 2017-11-20 02:32:51 |<\/p>\n

| 15 |\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 3942 | 3\u00a0\u00a0\u00a0 | \u6d4b\u8bd56\u00a0\u00a0\u00a0 | 9.jpg\u00a0 | 10.jpg | 2017-11-20 02:34:27 |<\/p>\n

+\u2014-+\u2014\u2014\u2014\u2014-+\u2014\u2014+\u2014\u2014\u2014-+\u2014\u2014\u2013+\u2014\u2014\u2013+\u2014\u2014\u2014\u2014\u2014\u2014\u2014+<\/p>\n

5 rows in set (0.01 sec)<\/p>\n

\u5982\u679c\u8981\u6839\u636eresource_id\u548ctype\u6765\u6279\u91cf\u67e5\u8be2\u8bb0\u5f55\uff0c\u8be5\u5982\u4f55\u7f16\u5199Mybatis\u8bed\u53e5\uff1f<\/p>\n

2. <\/strong>\u89e3\u51b3\u65b9\u6848<\/strong><\/h3>\n

\u76f4\u63a5\u8d34\u51fa\u6765\u89e3\u51b3\u65b9\u6848\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n

Dao\u5c42\u63a5\u53e3\uff1a<\/p>\n

List<EntryResource> findByRidAndType(List<EntryResource> entryResources);<\/p>\n

XML\u8bed\u53e5\uff1a<\/p>\n

<select id=\u201dfindByRidAndType\u201d resultMap=\u201dentryResource\u201d parameterType=\u201dlist\u201d><\/p>\n

\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 SELECT<\/p>\n

\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 *<\/p>\n

\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 FROM<\/p>\n

\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 t_entry_resource a<\/p>\n

\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 WHERE<\/p>\n

<foreach collection=\u201dlist\u201d index=\u201dindex\u201d item=\u201dentryResources\u201d open=\u201d(\u201d close=\u201d)\u201d separator=\u201dor\u201d><\/p>\n

\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 ( `type`=#{entryResources.type} and resource_id=#{entryResources.resourceId} )<\/p>\n

<\/foreach><\/p>\n

<\/select><\/p>\n

\u8be5\u8bed\u53e5\u5229\u7528\u4e86mybatis\u7684foreach\u52a8\u6001\u62fc\u63a5SQL\u3002<\/p>\n

3. foreach<\/strong>\u5c5e\u6027<\/strong><\/h3>\n
\n\n\n\n\n\n\n\n\n\n\n
\u5c5e\u6027<\/strong><\/strong><\/td>\n\u63cf\u8ff0<\/strong><\/strong><\/td>\n<\/tr>\n<\/thead>\n
item<\/strong><\/td>\n\u5faa\u73af\u4f53\u4e2d\u7684\u5177\u4f53\u5bf9\u8c61\u3002\u652f\u6301\u5c5e\u6027\u7684\u70b9\u8def\u5f84\u8bbf\u95ee\uff0c\u5982item.age,item.info.details\u3002\u5177\u4f53\u8bf4\u660e\uff1a\u5728list\u548c\u6570\u7ec4\u4e2d\u662f\u5176\u4e2d\u7684\u5bf9\u8c61\uff0c\u5728map\u4e2d\u662fvalue\u3002\u8be5\u53c2\u6570\u4e3a\u5fc5\u9009\u3002<\/td>\n<\/tr>\n
collection<\/strong><\/td>\n\u8981\u505aforeach\u7684\u5bf9\u8c61\uff0c\u4f5c\u4e3a\u5165\u53c2\u65f6\uff0cList<?>\u5bf9\u8c61\u9ed8\u8ba4\u7528list\u4ee3\u66ff\u4f5c\u4e3a\u952e\uff0c\u6570\u7ec4\u5bf9\u8c61\u6709array\u4ee3\u66ff\u4f5c\u4e3a\u952e\uff0cMap\u5bf9\u8c61\u7528map\u4ee3\u66ff\u4f5c\u4e3a\u952e\u3002\u5f53\u7136\u5728\u4f5c\u4e3a\u5165\u53c2\u65f6\u53ef\u4ee5\u4f7f\u7528@Param(\u201ckeyName\u201d)\u6765\u8bbe\u7f6e\u952e\uff0c\u8bbe\u7f6ekeyName\u540e\uff0clist,array,map\u5c06\u4f1a\u5931\u6548\u3002 \u9664\u4e86\u5165\u53c2\u8fd9\u79cd\u60c5\u51b5\u5916\uff0c\u8fd8\u6709\u4e00\u79cd\u4f5c\u4e3a\u53c2\u6570\u5bf9\u8c61\u7684\u67d0\u4e2a\u5b57\u6bb5\u7684\u65f6\u5019\u3002\u4e3e\u4e2a\u4f8b\u5b50\uff1a\u5982\u679cUser\u6709\u5c5e\u6027List ids\u3002\u5165\u53c2\u662fUser\u5bf9\u8c61\uff0c\u90a3\u4e48\u8fd9\u4e2acollection = \u201cids\u201d\u5982\u679cUser\u6709\u5c5e\u6027Ids ids;\u5176\u4e2dIds\u662f\u4e2a\u5bf9\u8c61\uff0cIds\u6709\u4e2a\u5c5e\u6027List id;\u5165\u53c2\u662fUser\u5bf9\u8c61\uff0c\u90a3\u4e48collection = \u201cids.id\u201d\u4e0a\u9762\u53ea\u662f\u4e3e\u4f8b\uff0c\u5177\u4f53collection\u7b49\u4e8e\u4ec0\u4e48\uff0c\u5c31\u770b\u4f60\u60f3\u5bf9\u90a3\u4e2a\u5143\u7d20\u505a\u5faa\u73af\u3002\u8be5\u53c2\u6570\u4e3a\u5fc5\u9009\u3002<\/td>\n<\/tr>\n
separator<\/strong><\/td>\n\u5143\u7d20\u4e4b\u95f4\u7684\u5206\u9694\u7b26\uff0c\u4f8b\u5982\u5728in()\u7684\u65f6\u5019\uff0cseparator=\u201d,\u201d\u4f1a\u81ea\u52a8\u5728\u5143\u7d20\u4e2d\u95f4\u7528\u201c,\u201c\u9694\u5f00\uff0c\u907f\u514d\u624b\u52a8\u8f93\u5165\u9017\u53f7\u5bfc\u81f4sql\u9519\u8bef\uff0c\u5982in(1,2,)\u8fd9\u6837\u3002\u8be5\u53c2\u6570\u53ef\u9009\u3002<\/td>\n<\/tr>\n
open<\/strong><\/td>\nforeach\u4ee3\u7801\u7684\u5f00\u59cb\u7b26\u53f7\uff0c\u4e00\u822c\u662f(\u548cclose=\u201d)\u201d\u5408\u7528\u3002\u5e38\u7528\u5728in(),values()\u65f6\u3002\u8be5\u53c2\u6570\u53ef\u9009\u3002<\/td>\n<\/tr>\n
close<\/strong><\/td>\nforeach\u4ee3\u7801\u7684\u5173\u95ed\u7b26\u53f7\uff0c\u4e00\u822c\u662f)\u548copen=\u201d(\u201c\u5408\u7528\u3002\u5e38\u7528\u5728in(),values()\u65f6\u3002\u8be5\u53c2\u6570\u53ef\u9009\u3002<\/td>\n<\/tr>\n
index<\/strong><\/td>\n\u5728list\u548c\u6570\u7ec4\u4e2d,index\u662f\u5143\u7d20\u7684\u5e8f\u53f7\uff0c\u5728map\u4e2d\uff0cindex\u662f\u5143\u7d20\u7684key\uff0c\u8be5\u53c2\u6570\u53ef\u9009\u3002<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n

4. foreach<\/strong>\u7684\u51e0\u79cd\u7528\u6cd5<\/strong><\/h3>\n

(1) select count(*) from users id in (x1,x2,x3,\u2026)<\/p>\n

<select id=\u201dcountByUserList\u201d resultType=\u201dint\u201d parameterType=\u201dlist\u201d>\u00a0\u00a0\u00a0<\/p>\n

select count(*) from users\u00a0\u00a0\u00a0<\/p>\n

\u00a0 <where>\u00a0\u00a0\u00a0<\/p>\n

\u00a0\u00a0\u00a0 id in\u00a0\u00a0\u00a0<\/p>\n

\u00a0\u00a0\u00a0 <foreach item=\u201ditem\u201d collection=\u201dlist\u201d separator=\u201d,\u201d open=\u201d(\u201d close=\u201d)\u201d index=\u201d\u201d>\u00a0\u00a0\u00a0<\/p>\n

\u00a0\u00a0\u00a0\u00a0\u00a0 #{item.id, jdbcType=NUMERIC}\u00a0\u00a0\u00a0<\/p>\n

\u00a0\u00a0\u00a0 <\/foreach>\u00a0\u00a0\u00a0<\/p>\n

\u00a0 <\/where>\u00a0\u00a0\u00a0<\/p>\n

<\/select><\/p>\n

(2) select count(*) from key_cols where col_a = ? AND col_b = ?<\/p>\n

<select id=\u201dsel_key_cols\u201d resultType=\u201dint\u201d>\u00a0\u00a0\u00a0<\/p>\n

\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 select count(*) from key_cols where\u00a0\u00a0\u00a0<\/p>\n

<foreach item=\u201ditem\u201d index=\u201dkey\u201d collection=\u201dmap\u201d\u00a0 open=\u201d\u201d separator=\u201dAND\u201d close=\u201d\u201d><\/p>\n

\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 ${key} = #{item}<\/p>\n

<\/foreach>\u00a0\u00a0\u00a0<\/p>\n

<\/select>\u00a0<\/p>\n

(3) select * from t_news n where n.tags like ? or n.tags like ?<\/p>\n

<select id=\u201dselectTestForEach\u201d parameterType=\u201dNews\u201d resultMap=\u201dNewsResultMapper\u201d><\/p>\n

\u00a0 select * from t_news n where<\/p>\n

\u00a0 <foreach collection=\u201dlistTag\u201d index=\u201dindex\u201d item=\u201dtag\u201d open=\u201d\u201d separator=\u201dor\u201d close=\u201d\u201d><\/p>\n

\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 n.tags like\u00a0 \u2018%\u2019||#{tag}||\u2019%\u2019<\/p>\n

\u00a0 <\/foreach><\/p>\n

<select><\/p>\n

\u5ef6\u4f38\u9605\u8bfb\uff1a<\/strong><\/p>\n

\u4e8c\u3001MongoDB\u662f\u4ec0\u4e48<\/strong><\/h2>\n

MongoDB \u662f\u6587\u6863\u578b\u6570\u636e\u5e93\u7684\u4ee3\u8868\uff0c\u6570\u636e\u6a21\u578b\u57fa\u4e8e Bson\uff0c\u800c Elasticsearch \u7684\u6587\u6863\u6570\u636e\u6a21\u578b\u662f Json\uff0cBson \u672c\u8d28\u662f Json \u7684\u4e00\u79cd\u6269\u5c55\uff0c\u53ef\u4ee5\u76f8\u4e92\u76f4\u63a5\u8f6c\u6362\uff0c\u4e14\u5b83\u4eec\u7684\u6570\u636e\u6a21\u5f0f\u90fd\u662f\u53ef\u4ee5\u81ea\u7531\u6269\u5c55\u7684\uff0c\u57fa\u672c\u65e0\u9650\u5236\u3002MongoDB \u672c\u8eab\u5b9a\u4f4d\u4e0e\u5173\u7cfb\u578b\u6570\u636e\u5e93\u7ade\u4e89\uff0c\u652f\u6301\u4e25\u683c\u7684\u4e8b\u52a1\u9694\u79bb\u673a\u5236\uff0c\u5728\u8fd9\u4e2a\u5c42\u9762\u5b9e\u9645\u4e0a\u4e0e Elasticsearch \u4ea7\u54c1\u5b9a\u4f4d\u4e0d\u4e00\u6837\uff0c\u4f46\u5b9e\u9645\u5de5\u4f5c\u4e2d\uff0c\u51e0\u4e4e\u6ca1\u6709\u516c\u53f8\u4f1a\u5c06\u6838\u5fc3\u4e1a\u52a1\u6570\u636e\u653e\u5728 MongoDB \u4e0a\uff0c\u5173\u7cfb\u578b\u6570\u636e\u5e93\u4f9d\u7136\u662f\u540d\u5217\u524d\u8305\u9009\u62e9\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"MyBatis\u4e2d\u53c2\u6570\u662fList\u7c7b\u578b\u65f6\u53ef\u4ee5\u7528foreach\u3002 foreach\u7684\u4e3b\u8981\u7528\u5728\u6784\u5efain\u6761\u4ef6\u4e2d\uff0c\u5b83\u53ef\u4ee5\u5728S […]","protected":false},"author":1,"featured_media":31520,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[37],"tags":[],"acf":[],"_links":{"self":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/posts\/31519"}],"collection":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/comments?post=31519"}],"version-history":[{"count":0,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/posts\/31519\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/media\/31520"}],"wp:attachment":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/media?parent=31519"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/categories?post=31519"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/tags?post=31519"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}