Mongodb两表关联查询

db.t1.aggregate([
    {"$lookup": {"from": "t2",  // 关联的表
                 "localField": "name",
                 "foreignField": "name",
                 "as": "add"},},
    {"$unwind": "$add"}, // 数组分割
    {$project: {"_id" : 0 ,"add" : {"_id" : 0 ,"name" :0}}},  // 不展示的数据
    {$out: "t3"}  //   结果数据保存 
    
           
]).pretty()