{"id":312,"date":"2012-03-16T20:43:55","date_gmt":"2012-03-16T12:43:55","guid":{"rendered":"http:\/\/www.royalwzy.com\/?p=312"},"modified":"2014-01-16T20:58:26","modified_gmt":"2014-01-16T12:58:26","slug":"mongodb%e5%ad%a6%e4%b9%a003-%e8%81%9a%e5%90%88%e6%93%8d%e4%bd%9c%e6%b8%b8%e6%a0%87%e7%9a%84%e4%bd%bf%e7%94%a8%e5%8f%8a%e6%8e%92%e5%ba%8f%e5%88%86%e9%a1%b5%e6%93%8d%e4%bd%9c","status":"publish","type":"post","link":"http:\/\/www.royalwzy.com\/?p=312","title":{"rendered":"MongoDB\u5b66\u4e6003–\u805a\u5408\u64cd\u4f5c,\u6e38\u6807\u7684\u4f7f\u7528\u53ca\u6392\u5e8f\u5206\u9875\u64cd\u4f5c"},"content":{"rendered":"
\u805a\u5408\u64cd\u4f5c,\u6e38\u6807\u7684\u4f7f\u7528\u53ca\u6392\u5e8f\u5206\u9875\u64cd\u4f5c<\/p>\n
\n
    \n
  1. \u805a\u5408\u64cd\u4f5c:\n
      \n
    1. count:\u67e5\u770b\u7b26\u5408\u67d0\u4e9b\u6761\u4ef6\u7684\u96c6\u5408\u4e2d\u8bb0\u5f55\u7684\u4e2a\u6570;\n
        \n
      1. \u67e5\u770b\u96c6\u5408user\u7684\u8bb0\u5f55\u6570:db.user.count(); \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\"\"<\/li>\n
      2. \u67e5\u770b\u96c6\u5408user\u4e2d\u5e74\u9f84\u5927\u4e8e20\u7684\u8bb0\u5f55\u7684\u4e2a\u6570:db.user.count({“age”:{$gt:20}}); \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\"\"<\/li>\n<\/ol>\n<\/li>\n
      3. distinct:\u67e5\u770b\u96c6\u5408\u4e2d\u67d0\u4e2a\u5c5e\u6027\u7684\u72ec\u7acb\u5b58\u5728\u7684\u4e2a\u6570;\n
          \n
        1. \u83b7\u5f97\u4e0d\u540c\u5e74\u9f84\u7684\u6570\u7ec4:db.user.distinct(“age”); \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\u00a0\"\"<\/li>\n
        2. \u83b7\u5f97\u4e0d\u540c\u5e74\u9f84\u503c\u7684\u4e2a\u6570:db.user.distinct(“age”).length; \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\u00a0\"\"<\/li>\n<\/ol>\n<\/li>\n
        3. group:\u5bf9\u96c6\u5408\u6309\u7167\u67d0\u4e00\u5c5e\u6027\u5206\u7ec4,\u5f62\u6210\u4e00\u4e2aK-V\u6a21\u578b;\n
            \n
          1. \u8bed\u6cd5:db.mycoll.group( { key : …, initial: …, reduce : …\u00a0[, finalize: …]\u00a0[, condition: …] } );\n
              \n
            1. key:\u5206\u7ec4\u7684\u952e;<\/li>\n
            2. initial:\u6bcf\u4e2a\u5206\u7ec4\u4f7f\u7528\u7684\u521d\u59cb\u5316\u51fd\u6570;<\/li>\n
            3. reduce:\u6b64\u51fd\u6570\u7684\u7b2c\u4e00\u4e2a\u53c2\u6570\u662f\u5f53\u524d\u7684\u6587\u6863\u5bf9\u8c61,\u7b2c\u4e8c\u4e2a\u53c2\u6570\u662f\u4e0a\u6b21\u51fd\u6570(\u5373initial\u51fd\u6570)\u64cd\u4f5c\u7684\u7d2f\u8ba1\u5bf9\u8c61,\u6709\u591a\u5c11\u4e2a\u6587\u6863,$reduce\u5c31\u4f1a\u8c03\u7528\u591a\u5c11\u6b21;<\/li>\n
            4. finalize:\u6bcf\u4e00\u7ec4\u6587\u6863\u6267\u884c\u5b8c\u4e4b\u540e,\u4f1a\u89e6\u53d1\u6267\u884c\u7684\u4e00\u4e2a\u51fd\u6570,\u53c2\u6570\u662f\u4e0a\u6b21\u51fd\u6570(\u5373initial\u51fd\u6570)\u64cd\u4f5c\u7684\u7d2f\u8ba1\u5bf9\u8c61;<\/li>\n
            5. condtion:\u8fc7\u6ee4\u6761\u4ef6;<\/li>\n<\/ol>\n<\/li>\n
            6. \u6309\u7167\u5e74\u9f84\u5206\u7ec4\u7684\u4f8b\u5b50:db.user.group({key:{age:true}, initial:{user:[]}, reduce:function(cur, prev){prev.user.push(cur.name);}}),push\u51fd\u6570\u662f\u628a\u4e00\u4e2a\u503c\u52a0\u5165\u5230\u6570\u7ec4\u4e2d; \u00a0 \u00a0 \u00a0\u00a0\"\"<\/li>\n
            7. \u6309\u7167\u5e74\u9f84\u5206\u7ec4,\u8fc7\u6ee4\u6389\u5e74\u9f84\u5927\u4e8e25\u7684\u8bb0\u5f55,\u5e76\u4e14\u6dfb\u52a0\u4e00\u4e2a\u7528\u6237\u6570\u91cf\u7684\u5c5e\u6027count:db.user.group({key:{age:true}, initial:{user:[]}, reduce:function(cur, prev){prev.user.push(cur.name);}, finalize:function(prev){prev.count=prev.user.length;}, condition:{age:{$lte:25}}}); \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\u00a0\"\"<\/li>\n<\/ol>\n<\/li>\n
            8. mapReduce:\u5176\u5b9e\u662f\u4e00\u79cd\u7f16\u7a0b\u6a21\u578b,\u7528\u5728\u5206\u5e03\u5f0f\u8ba1\u7b97\u4e2d.\u53ef\u4ee5\u628a\u95ee\u9898\u5212\u5206\u4e3a\u591a\u4e2a\u4e0d\u540c\u7684\u90e8\u5206\u5e76\u5206\u53d1\u5230\u4e0d\u540c\u7684\u670d\u52a1\u5668\u5e76\u884c\u5904\u7406,\u6bcf\u53f0\u670d\u52a1\u5668\u90fd\u628a\u5206\u914d\u7ed9\u81ea\u5df1\u7684\u4e00\u90e8\u5206\u5904\u7406\u5b8c\u6210\u540e\u628a\u7ed3\u679c\u96c6\u8fd4\u56de\u7ed9\u4e3b\u670d\u52a1\u5668,\u4e3b\u670d\u52a1\u5668\u6c47\u603b\u7ed3\u679c\u540e\u5b8c\u6210\u95ee\u9898\u7684\u5904\u7406;\n
                \n
              1. \u8bed\u6cd5:db.mycoll.mapReduce( mapFunction , reduceFunction , <optional params> );\n
                  \n
                1. mapFunction:\u6620\u5c04\u51fd\u6570,\u91cc\u9762\u4f1a\u8c03\u7528emit(key, value),\u96c6\u5408\u4f1a\u6309\u7167\u6307\u5b9a\u7684key\u8fdb\u884c\u6620\u5c04\u5206\u7ec4;<\/li>\n
                2. reduceFunction:;\u7b80\u5316\u51fd\u6570,\u4f1a\u5bf9map\u5206\u7ec4\u540e\u7684\u6570\u636e\u8fdb\u884c\u5206\u7ec4\u7b80\u5316.\u5176\u4e2dreduce(key, value)\u4e2d\u7684key\u5c31\u662femit\u4e2d\u7684key,value\u4e3aemit\u5206\u7ec4\u540e\u7684emit(value)\u7684\u96c6\u5408,\u5b83\u6709\u4e00\u4e2a\u6216\u8005\u591a\u4e2a\u5bf9\u5e94\u4e8e\u952e\u7684\u6587\u6863\u7ec4\u6210;<\/li>\n
                3. \u53ef\u9009\u53c2\u6570;<\/li>\n<\/ol>\n<\/li>\n
                4. \u539f\u7406:map\u9996\u5148\u5c06\u6587\u6863\u6620\u5c04\u5230\u96c6\u5408\u5e76\u64cd\u4f5c\u6587\u6863,\u8fd9\u4e00\u6b65\u53ef\u80fd\u4ea7\u751f\u591a\u4e2a\u952e\u548c\u591a\u4e2a\u503c\u6216\u8005\u4ec0\u4e48\u4e5f\u6ca1\u6709(\u6587\u6863\u4e2d\u8981\u5904\u7406\u7684\u503c\u4e3a\u7a7a).\u800c\u540e\u6309\u7167\u952e\u5206\u7ec4,\u5e76\u5c06\u4ea7\u751f\u7684\u503c\u7ec4\u6210\u5217\u8868\u653e\u5230\u5bf9\u5e94\u7684\u952e\u4e2d,reduce\u5219\u628a\u5217\u8868\u4e2d\u7684\u503c\u5316\u7b80\u4e3a\u4e00\u4e2a\u503c,\u8fd9\u4e2a\u503c\u88ab\u8fd4\u56de,\u800c\u540e\u7ee7\u7eed\u6309\u952e\u5206\u7ec4,\u8fdb\u884c\u5316\u7b80,\u76f4\u5230\u6bcf\u4e2a\u952e\u5728\u5217\u8868\u4e2d\u53ea\u6709\u4e00\u4e2a\u503c\u4e3a\u6b62,\u8fd9\u4e2a\u503c\u4e5f\u5c31\u662f\u6700\u7ec8\u7ed3\u679c;<\/li>\n
                5. \u4f8b\u5b50;<\/li>\n<\/ol>\n<\/li>\n<\/ol>\n<\/li>\n
                6. \u6e38\u6807\u7684\u4f7f\u7528:\n
                    \n
                  1. \u4f7f\u7528while\u5faa\u73af\u904d\u5386\u8f93\u51fa:var cursor=db.user.find();\u00a0while(cursor.hasNext()) { printjson(cursor.next()); };(\u5176\u4e2dhasNext()\u51fd\u6570\u5224\u65ad\u662f\u5426\u6709\u8bb0\u5f55,next()\u51fd\u6570\u8fd4\u56de\u4e0b\u4e00\u6761\u8bb0\u5f55) \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\u00a0\"\"<\/li>\n
                  2. pringjson()\u51fd\u6570\u662f\u5185\u7f6e\u51fd\u6570,\u80fd\u591f\u5c06\u7ed3\u679c\u8f93\u51fa\u4e3ajson\u683c\u5f0f;<\/li>\n
                  3. \u5f97\u5230\u6570\u636e\u96c6\u96c6\u5408,\u904d\u5386\u5b8c\u4e4b\u540e\u6e38\u6807\u4fbf\u9500\u6bc1;<\/li>\n
                  4. \u4f7f\u7528forEach()\u51fd\u6570\u904d\u5386:db.user.find().forEach(printjson); \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\"\"<\/li>\n
                  5. \u50cf\u8bbf\u95ee\u6570\u7ec4\u4e00\u6837\u4f7f\u7528\u6e38\u6807:var cursor=db.user.find();printjson(cursor[0]);(\u4f1a\u628a\u8bbf\u95ee\u7684\u6570\u636e\u90fd\u52a0\u8f7dram\u4e2d,\u5982\u679c\u6570\u636e\u91cf\u5f88\u5927\u7684\u8bdd\u975e\u5e38\u6d88\u8017\u5185\u5b58) \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\"\"<\/li>\n
                  6. \u76f4\u63a5\u8f6c\u6362\u6210\u6570\u7ec4\u8bbf\u95ee:var array=db.user.find().toArray();array[0]; \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\"\"<\/li>\n<\/ol>\n<\/li>\n
                  7. \u6392\u5e8f\u64cd\u4f5c:\n
                      \n
                    1. \u8bed\u6cd5:db.mycoll.find().sort({col:value, …});\n
                        \n
                      1. col:\u8868\u793a\u6309\u7167\u6392\u5e8f\u7684\u5217;<\/li>\n
                      2. value:\u53ef\u4ee5\u53d61\u548c-1,1\u8868\u793a\u5347\u5e8f,-1\u8868\u793a\u964d\u5e8f;<\/li>\n
                      3. \u67e5\u627e\u6240\u6709\u8bb0\u5f55,\u5e76\u6309\u7167\u5e74\u9f84\u5347\u5e8f,\u540d\u79f0\u964d\u5e8f\u663e\u793a:db.user.find().sort({“age”:1, “name”:-1}),select name, age from user order by age desc, name asc; \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\"\"<\/li>\n<\/ol>\n<\/li>\n
                      4. \u8fd8\u53ef\u4ee5\u901a\u8fc7\u5176\u5b83\u65b9\u6cd5\u5b9e\u73b0,db.mycoll.find([query], [fields])\u64cd\u4f5c\u662f\u6839\u636equery\u8fc7\u6ee4\u8bb0\u5f55,\u5148\u540e\u663e\u793afields\u91cc\u9762\u6307\u5b9a\u7684\u5217,\u5982\u679cquery\u7ed9\u9ed8\u8ba4\u7684\u8bdd({}\u5c31\u662f\u9ed8\u8ba4\u7684\u53c2\u6570),\u53ea\u9700\u8981\u6307\u5b9a\u5217\u540d\u53ca\u6392\u5e8f\u65b9\u5f0f\u5373\u53ef:select name, age from user order by age desc, name asc; \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\u00a0\"\"<\/li>\n
                      5. \u5148\u6309\u5e74\u9f84\u5347\u5e8f,\u7136\u540e\u6309\u7167\u540d\u79f0\u5347\u5e8f\u6392\u5e8f:select name from user order by age asc, name asc; \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\"\"<\/li>\n<\/ol>\n<\/li>\n
                      6. \u5206\u9875\u64cd\u4f5c:\n
                          \n
                        1. \u4f7f\u7528db.mycoll.find().skip(n)\u64cd\u4f5c\u548cdb.mycoll.find().limit(n)\u5b9e\u73b0,\u524d\u8005\u662f\u8df3\u8fc7\u4e4b\u524d\u591a\u5c11\u6761\u8bb0\u5f55,\u540e\u8005\u662f\u663e\u793a\u591a\u5c11\u6761\u8bb0\u5f55:skip((pageIndex-1) * pageSize).limit(pageSize);<\/li>\n
                        2. \u6392\u5e8f\u540e\u7684\u7ed3\u679c,\u6bcf\u9875\u4e24\u6761\u8bb0\u5f55,\u663e\u793a\u7b2c\u4e8c\u9875:db.user.find().sort({“age”:1, “name”:-1}).skip(2).limit(2); \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\u00a0\"\"<\/li>\n<\/ol>\n<\/li>\n<\/ol>\n
                          <\/div>\n<\/div>\n
                          <\/div>\n
                          — \u6d4b\u8bd5\u6570\u636e;<\/div>\n
                          db.user.drop()<\/div>\n
                          db.user.insert({“name”:”jack”, “age”:20})<\/div>\n
                          db.user.insert({“name”:”joe”, “age”:22})<\/div>\n
                          db.user.insert({“name”:”mary”, “age”:26})<\/div>\n
                          db.user.insert({“name”:”kobe”, “age”:20})<\/div>\n
                          db.user.insert({“name”:”wade”, “age”:22})<\/div>\n
                          db.user.insert({“name”:”yi”, “age”:22})<\/div>\n
                          db.user.find()<\/div>\n
                          \"\"<\/div>\n
                          <\/div>\n
                          <\/div>\n
                          — mapReduce\u64cd\u4f5c;<\/div>\n
                          1.\u521b\u5efamap\u51fd\u6570;<\/div>\n
                          function\u00a0map(){ emit(this.age, {count:1}); }<\/div>\n
                          \"\"<\/div>\n
                          <\/div>\n
                          2.\u521b\u5efareduce\u51fd\u6570;<\/div>\n
                          function\u00a0reduce(key, value){<\/div>\n
                          \u00a0 \u00a0 \u00a0var result = {count:0};<\/div>\n
                          \u00a0 \u00a0 \u00a0for (var i = 0; i < value.length; i++){<\/div>\n
                          \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 result.count += value[i].count;<\/div>\n
                          \u00a0\u00a0\u00a0\u00a0\u00a0}<\/div>\n
                          \u00a0 \u00a0 \u00a0return result;<\/div>\n
                          }<\/div>\n
                          \"\"<\/div>\n
                          <\/div>\n
                          3.\u6267\u884cmapReduce\u64cd\u4f5c,\u5e76\u628a\u7ed3\u679c\u96c6\u5b58\u653e\u5728\u96c6\u5408collection\u4e2d;<\/div>\n
                          db.user.mapReduce(map, reduce, {out:”collection”})<\/div>\n
                          \"\"<\/div>\n
                          result:\u5b58\u653e\u96c6\u5408\u540d;<\/div>\n
                          timeMillis:\u6267\u884c\u7684\u65f6\u95f4,\u5355\u4f4d\u662f\u6beb\u79d2;<\/div>\n
                          input:\u4f20\u5165\u6587\u6863\u7684\u4e2a\u6570;<\/div>\n
                          emit:emit\u51fd\u6570\u88ab\u8c03\u7528\u7684\u6b21\u6570;<\/div>\n
                          reduce:reduce\u51fd\u6570\u88ab\u8c03\u7528\u7684\u6b21\u6570;<\/div>\n
                          output:\u6700\u540e\u8fd4\u56de\u6587\u6863\u7684\u4e2a\u6570;<\/div>\n
                          <\/div>\n
                          4.\u67e5\u770bcollection\u4e2d\u7684\u7ed3\u679c;<\/div>\n
                          db.collection.find()<\/div>\n
                          \"\"<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

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