{"id":21579,"date":"2024-01-02T11:49:30","date_gmt":"2024-01-02T11:49:30","guid":{"rendered":"https:\/\/server.hk\/blog\/21579\/"},"modified":"2024-11-14T10:30:26","modified_gmt":"2024-11-14T02:30:26","slug":"mongodb-glossary-read-operation","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/21579\/","title":{"rendered":"MongoDB\u8a5e\u5f59\u8868 – \u8b80\u53d6\u64cd\u4f5c"},"content":{"rendered":"

MongoDB\u8a5e\u5f59\u8868 – \u8b80\u53d6\u64cd\u4f5c<\/h1>\n

\u5728\u6578\u64da\u5eab\u7684\u4e16\u754c\u4e2d\uff0cMongoDB \u5df2\u6210\u70ba\u56e0\u5176\u9748\u6d3b\u6027\u3001\u53ef\u64f4\u5c55\u6027\u53ca\u6613\u7528\u6027\u800c\u5099\u53d7\u9752\u775e\u7684\u9078\u64c7\u3002\u4f5c\u70ba\u4e00\u6b3e NoSQL \u6578\u64da\u5eab\uff0cMongoDB \u63d0\u4f9b\u4e86\u4e00\u7cfb\u5217\u5ee3\u6cdb\u7684\u529f\u80fd\u548c\u7279\u6027\uff0c\u4ee5\u6eff\u8db3\u73fe\u4ee3\u61c9\u7528\u7a0b\u5e8f\u7684\u9700\u6c42\u3002\u8981\u5b8c\u5168\u7406\u89e3 MongoDB \u53ca\u5176\u80fd\u529b\uff0c\u719f\u6089\u8207\u5176\u76f8\u95dc\u7684\u5404\u7a2e\u8853\u8a9e\u662f\u81f3\u95dc\u91cd\u8981\u7684\u3002\u5728\u672c\u6587\u4e2d\uff0c\u6211\u5011\u5c07\u63a2\u8a0e MongoDB \u8a5e\u5f59\u4e2d\u7684\u4e00\u500b\u8853\u8a9e\u2014\u2014\u8b80\u53d6\u64cd\u4f5c\u3002<\/p>\n

\u4ec0\u9ebc\u662f MongoDB \u4e2d\u7684\u8b80\u53d6\u64cd\u4f5c\uff1f<\/h2>\n

MongoDB \u4e2d\u7684\u8b80\u53d6\u64cd\u4f5c\u6307\u7684\u662f\u5f9e MongoDB \u6578\u64da\u5eab\u4e2d\u6aa2\u7d22\u6578\u64da\u7684\u904e\u7a0b\u3002\u5b83\u5141\u8a31\u7528\u6236\u6839\u64da\u7279\u5b9a\u6a19\u6e96\u67e5\u8a62\u6578\u64da\u5eab\u4e26\u7372\u53d6\u6240\u9700\u7684\u4fe1\u606f\u3002MongoDB \u63d0\u4f9b\u4e86\u4e00\u500b\u5f37\u5927\u800c\u9748\u6d3b\u7684\u67e5\u8a62\u6a5f\u5236\uff0c\u4f7f\u5f97\u7528\u6236\u80fd\u5920\u57f7\u884c\u8907\u96dc\u7684\u641c\u7d22\uff0c\u4e26\u9ad8\u6548\u5730\u6aa2\u7d22\u6578\u64da\u3002<\/p>\n

MongoDB \u4e2d\u7684\u8b80\u53d6\u64cd\u4f5c\u985e\u578b<\/h2>\n

\u5728 MongoDB \u4e2d\u53ef\u7528\u7684\u8b80\u53d6\u64cd\u4f5c\u6709\u5e7e\u7a2e\uff1a<\/p>\n

1. find()<\/h3>\n

find()<\/code> \u65b9\u6cd5\u662f\u5f9e MongoDB \u96c6\u5408\u4e2d\u6aa2\u7d22\u6578\u64da\u7684\u4e3b\u8981\u65b9\u5f0f\u3002\u5b83\u5141\u8a31\u7528\u6236\u6307\u5b9a\u67e5\u8a62\u689d\u4ef6\uff0c\u4e26\u6aa2\u7d22\u7b26\u5408\u8a72\u689d\u4ef6\u7684\u6587\u6a94\u3002find()<\/code> \u65b9\u6cd5\u652f\u6301\u591a\u7a2e\u67e5\u8a62\u904b\u7b97\u7b26\uff0c\u4f8b\u5982 $eq<\/code>\u3001$gt<\/code>\u3001$lt<\/code> \u7b49\uff0c\u4ee5\u57f7\u884c\u9ad8\u7d1a\u641c\u7d22\u3002<\/p>\n

2. findOne()<\/h3>\n

findOne()<\/code> \u65b9\u6cd5\u985e\u4f3c\u65bc find()<\/code> \u65b9\u6cd5\uff0c\u4f46\u50c5\u8fd4\u56de\u7b2c\u4e00\u500b\u7b26\u5408\u67e5\u8a62\u689d\u4ef6\u7684\u6587\u6a94\u3002\u7576\u60a8\u53ea\u9700\u8981\u55ae\u4e00\u7d50\u679c\u6216\u5e0c\u671b\u7372\u53d6\u7b2c\u4e00\u500b\u5339\u914d\u7684\u6587\u6a94\u6642\uff0c\u5b83\u975e\u5e38\u6709\u7528\u3002<\/p>\n

3. count()<\/h3>\n

count()<\/code> \u65b9\u6cd5\u5141\u8a31\u7528\u6236\u78ba\u5b9a\u8207\u7279\u5b9a\u67e5\u8a62\u5339\u914d\u7684\u6587\u6a94\u6578\u91cf\u3002\u5b83\u4ee5\u6574\u6578\u5f62\u5f0f\u8fd4\u56de\u8a08\u6578\uff0c\u63d0\u4f9b\u6709\u50f9\u503c\u7684\u7d50\u679c\u96c6\u5927\u5c0f\u4fe1\u606f\u3002<\/p>\n

4. distinct()<\/h3>\n

distinct()<\/code> \u65b9\u6cd5\u7528\u65bc\u6aa2\u7d22\u96c6\u5408\u4e2d\u7279\u5b9a\u5b57\u6bb5\u7684\u552f\u4e00\u503c\u3002\u5b83\u6d88\u9664\u4e86\u91cd\u8907\u503c\uff0c\u8fd4\u56de\u4e00\u500b\u4e0d\u91cd\u8907\u503c\u7684\u5217\u8868\uff0c\u9019\u5c0d\u65bc\u6578\u64da\u5206\u6790\u548c\u532f\u7e3d\u975e\u5e38\u6709\u7528\u3002<\/p>\n

5. aggregate()<\/h3>\n

aggregate()<\/code> \u65b9\u6cd5\u4f7f\u7528\u6237\u80fd\u591f\u5bf9 MongoDB \u96c6\u5408\u6267\u884c\u9ad8\u7ea7\u6570\u636e\u805a\u5408\u64cd\u4f5c\u3002\u5b83\u652f\u6301\u5404\u79cd\u805a\u5408\u9636\u6bb5\uff0c\u4f8b\u5982 $match<\/code>\u3001$group<\/code>\u3001$sort<\/code> \u7b49\uff0c\u5141\u8bb8\u7528\u6237\u6839\u636e\u9700\u6c42\u5904\u7406\u548c\u8f6c\u6362\u6570\u636e\u3002<\/p>\n

MongoDB \u4e2d\u7684\u8b80\u53d6\u64cd\u4f5c\u793a\u4f8b<\/h2>\n

\u8b93\u6211\u5011\u770b\u770b\u4e00\u4e9b\u793a\u4f8b\uff0c\u4ee5\u4e86\u89e3 MongoDB \u4e2d\u8b80\u53d6\u64cd\u4f5c\u5982\u4f55\u5de5\u4f5c\uff1a<\/p>\n

\u793a\u4f8b 1\uff1a\u4f7f\u7528 find()<\/h3>\n
db.users.find({ age: { $gt: 25 } })\r\n<\/code><\/pre>\n
\u8a72\u67e5\u8a62\u6aa2\u7d22 “users” \u96c6\u5408\u4e2d\u6240\u6709 “age” \u5b57\u6bb5\u5927\u65bc 25 \u7684\u6587\u6a94\u3002<\/p>\n
\u793a\u4f8b 2\uff1a\u4f7f\u7528 findOne()<\/h3>\n
db.users.findOne({ name: \"John\" })\r\n<\/code><\/pre>\n
\u8a72\u67e5\u8a62\u6aa2\u7d22 “users” \u96c6\u5408\u4e2d “name” \u5b57\u6bb5\u7b49\u65bc “John” \u7684\u7b2c\u4e00\u500b\u6587\u6a94\u3002<\/p>\n
\u793a\u4f8b 3\uff1a\u4f7f\u7528 count()<\/h3>\n
db.users.count({ status: \"active\" })\r\n<\/code><\/pre>\n
\u8a72\u67e5\u8a62\u8fd4\u56de “users” \u96c6\u5408\u4e2d “status” \u5b57\u6bb5\u70ba “active” \u7684\u6587\u6a94\u6578\u91cf\u3002<\/p>\n
\u793a\u4f8b 4\uff1a\u4f7f\u7528 distinct()<\/h3>\n
db.users.distinct(\"city\")\r\n<\/code><\/pre>\n
\u8a72\u67e5\u8a62\u5f9e “users” \u96c6\u5408\u4e2d\u6aa2\u7d22 “city” \u5b57\u6bb5\u7684\u6240\u6709\u552f\u4e00\u503c\u3002<\/p>\n
\u793a\u4f8b 5\uff1a\u4f7f\u7528 aggregate()<\/h3>\n
db.orders.aggregate([\r\n  { $match: { status: \"completed\" } },\r\n  { $group: { _id: \"$customer\", total: { $sum: \"$amount\" } } }\r\n])\r\n<\/code><\/pre>\n
\u8a72\u67e5\u8a62\u5c0d “orders” \u96c6\u5408\u57f7\u884c\u805a\u5408\u64cd\u4f5c\u3002\u5b83\u5339\u914d “status” \u5b57\u6bb5\u8a2d\u7f6e\u70ba “completed” \u7684\u6587\u6a94\uff0c\u4e26\u6839\u64da “customer” \u5b57\u6bb5\u9032\u884c\u5206\u7d44\uff0c\u7136\u5f8c\u8a08\u7b97\u6bcf\u4f4d\u5ba2\u6236\u7684\u7e3d\u91d1\u984d\u3002<\/p>\n
\u7d50\u8ad6<\/h2>\n
\u8b80\u53d6\u64cd\u4f5c\u5728\u5f9e MongoDB \u6578\u64da\u5eab\u4e2d\u6aa2\u7d22\u6578\u64da\u65b9\u9762\u626e\u6f14\u8457\u81f3\u95dc\u91cd\u8981\u7684\u89d2\u8272\u3002\u7406\u89e3\u4e0d\u540c\u985e\u578b\u7684\u8b80\u53d6\u64cd\u4f5c\u53ca\u5176\u6709\u6548\u7684\u4f7f\u7528\u65b9\u5f0f\uff0c\u80fd\u6975\u5927\u63d0\u5347\u60a8\u7684 MongoDB \u9ad4\u9a57\u3002\u7121\u8ad6\u60a8\u9700\u8981\u7372\u53d6\u55ae\u500b\u6587\u6a94\u9084\u662f\u57f7\u884c\u8907\u96dc\u7684\u6578\u64da\u805a\u5408\uff0cMongoDB \u90fd\u63d0\u4f9b\u4e86\u4e00\u6574\u5957\u8c50\u5bcc\u7684\u529f\u80fd\u4ee5\u6eff\u8db3\u60a8\u7684\u9700\u6c42\u3002<\/p>\n
\u5982\u9700\u4e86\u89e3\u66f4\u591a\u95dc\u65bc MongoDB \u53ca\u5176\u80fd\u529b\u7684\u4fe1\u606f\uff0c\u8acb\u8003\u616e\u63a2\u7d22 Server.HK<\/a>\uff0c\u9019\u662f\u4e00\u5bb6\u9818\u5148\u7684 VPS \u4e3b\u6a5f\u516c\u53f8\uff0c\u63d0\u4f9b\u53ef\u9760\u4e14\u53ef\u64f4\u5c55\u7684 MongoDB \u4e3b\u6a5f\u89e3\u6c7a\u65b9\u6848\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
MongoDB\u8a5e\u5f59\u8868 &#821...<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4925],"tags":[],"class_list":["post-21579","post","type-post","status-publish","format-standard","hentry","category-4925"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/21579","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=21579"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/21579\/revisions"}],"predecessor-version":[{"id":23867,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/21579\/revisions\/23867"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=21579"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=21579"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=21579"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}