DynamoDB的基本操作（一）

一、创建表

 1 var AWS = require("aws-sdk");
 2 AWS.config.update({
 3     region: "us-west-2",                          //使用哪个区域的aws服务
 4     endpoint: "http://localhost:8000" //dynamodb位置
 5 });
 6 var dynamodb = new AWS.DynamoDB();
 7
 8 var params = {
 9     TableName: "Movies",//表名
10     KeySchema: [       //主键
11         {AttributeName: "year", KeyType: "HASH"},  //Partition key 分区键
12         {AttributeName: "title", KeyType: "RANGE"}  //Sort key    排序键
13     ],
14     AttributeDefinitions: [//主键数据类型
15         {AttributeName: "year", AttributeType: "N"},//N Number
16         {AttributeName: "title", AttributeType: "S"}   //S String
17     ],
18     ProvisionedThroughput: { //DynamoDB吞吐量配置
19         ReadCapacityUnits: 10,
20         WriteCapacityUnits: 10
21     }
22 };
23 dynamodb.createTable(params, function (err, data) {
24     if (err) {
25         console.error("Unable to create table. Error JSON:", JSON.stringify(err, null, 2));
26     } else {
27         console.log("Created table. Table description JSON:", JSON.stringify(data, null, 2));
28     }
29 });

二、增加项

 var docClient = new AWS.DynamoDB.DocumentClient();
 var table = "Movies";
 var year = 2015;
 var title = "The Big New Movie";
 var params = {
     TableName: table,//要操作的表名
     Item: {
         "year": year,//主键-分区间
         "title": title,//主键-排序键
         "info": {     //其他属性
             "plot": "Nothing happens at all.", "rating": 0
         }
     }
 };
 console.log("Adding a new item...");
 docClient.put(params, function (err, data) {
     if (err) {
         console.error("Unable to add item. Error JSON:", JSON.stringify(err, null, 2));
     } else {
         console.log("Added item:", JSON.stringify(data, null, 2));
     }
 });

三、获取项

 var docClient = new AWS.DynamoDB.DocumentClient()
 var table = "Movies";//表名必须填
 var year = 2015;  //待查询的分区键
 var title = "The Big New Movie";//待查询的排序键   如果表建立时设置为复合主键的话，分区键排序键必须都存在
 var params = {TableName: table, Key: {"year": year, "title": title}};
 docClient.get(params, function (err, data) {
     if (err) {
         console.error("Unable to read item. Error JSON:", JSON.stringify(err, null, 2));
     } else {
         console.log("GetItem succeeded:", JSON.stringify(data, null, 2));
     }
 });

四、更新项

 var table = "Movies";
 var year = 2015;
 var title = "The Big New Movie"; // Update the item, unconditionally,
 var params = {
     TableName: table, Key: {
         "year": year,//分区键
         "title": title//排序键   主键在update接口必须
     }, UpdateExpression: "set info.rating = :r, info.plot=:p, info.actors=:a",//想要改变值的表达式
     ExpressionAttributeValues: {      //为想要改变的值赋值
         ":r": 5.5, ":p": "Everything happens all at once.", ":a": ["Larry", "Moe", "Curly"]
     }, ReturnValues: "UPDATED_NEW"//返回更新值，即下中data
 };
 console.log("Updating the item...");
 docClient.update(params, function (err, data) {
     console.log(data);
     if (err) {
         console.error("Unable to update item. Error JSON:", JSON.stringify(err, null, 2));
     } else {
         console.log("UpdateItem succeeded:", JSON.stringify(data, null, 2));
     }
 });

五、删除项

 var table = "Movies";
 var year = 2015;
 var title = "The Big New Movie";
 var params = {
     TableName: table,//待删除操作的表
     Key: {
         "year": year,//分区键
         "title": title//排序键
     },
     ExpressionAttributeNames:{"#u":"User"},
     ConditionExpression: "#u = :val",//删除条件表达式
     ExpressionAttributeValues: {
         ":val": 5.0   //条件值
     }
 };
 console.log("Attempting a conditional delete...");
 docClient.delete(params, function (err, data) {
     if (err) {
         console.error("Unable to delete item. Error JSON:", JSON.stringify(err, null, 2));
     } else {
         console.log("DeleteItem succeeded:", JSON.stringify(data, null, 2));
     }
 });

六、批量查询

 var params = {
  RequestItems: {
   "GsdSubDevices": {
    Keys: [
     {
      "Mac": "haha"
     },
     {
      "Mac": "111"
     },
     {
      "Mac": "222"
     }
    ]
   }
  }
 };
 console.log("requestArr===>" + JSON.stringify(requestArr));
 docClient.batchGet(params, function (err, data) {
  if (err) {
   console.error("Unable to read item. Error JSON:", JSON.stringify(err, null, 2));
  } else {

  }
 });

 推荐操作数据库时使用以上操作，操作DynamoDB数据库有两种方式，另一种见DynamoBD常见操作（二），这种方式比较繁琐，不推荐使用