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                # 建模 ## ER模型  關系數據庫或者ER圖,這其實是以實體(個體,類)為基礎的物理語言,因為關系是實體之間的關系,是由實體來(聯合)定義的,所以是實體在先,關系在后的.   當然,也有所謂的純關系項,比如學生成績(數學分數),既不屬于學生,也不屬于課程,而是它們的關系存在. * 三范式 * 笛卡爾積 * 關系:一對一,一對多,多對多 * SQL * 工具:powerdesigner、erwin 說明:常見的關系型數據庫來描述er模型比較多。我們用mongodb也是一樣的,處理查詢不太一樣以外,其他都是一樣的。 ## 實體 * 用戶(微信) * 課程 * 訂單 ## 關系 * 我的課程:1對多 - ## 微信用戶 ~~~ /** * Created by alfred on August 25th 2015, 6:11:46 pm. */ var mongoose = require('mongoose'); var Schema = mongoose.Schema; var MongooseDao = require('mongoosedao'); var wechatSchema = new Schema({ unionid : String, openid: {// from weixin openid type: String, required: true, index: { unique: true } }, nickname : String,// from weixin 昵稱 sex : String,// from weixin 性別 0->女 1->男 language : String,// from weixin 語言 city : String,// from weixin 城市 province : String,// from weixin country : String,// from weixin headimgurl : String,// from weixin 頭像路徑 privilege : [], // from weixin created_at : { type: Date, "default": Date.now } }); wechatSchema.statics.find_by_openid = function(openid, cb) { return this.findOne({ openid: openid }, cb); }; wechatSchema.statics.find_by_unionid = function(unionid, cb) { return this.findOne({ unionid: unionid }, cb); }; var Wechat = mongoose.model('Wechat', wechatSchema); var WechatDao = new MongooseDao(Wechat); module.exports = WechatDao; ~~~ ## 課程列表 ## 訂單
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