golang monogdb

package main


import (
"fmt"
"labix.org/v2/mgo"
"labix.org/v2/mgo/bson"
)


type Depta struct {
Id      string `bson:"_id"`
Count   int
Ename   string
Sal     int
Mgrsal  int
Subsal  int
Davgsal int
Dsumsal int
Dcount  int
}


func main() {
session, err := mgo.Dial("127.0.0.1")
if err != nil {
panic(err)
}
defer session.Close()
session.SetMode(mgo.Monotonic, true)
c := session.DB("lizd").C("dept")
fmt.Println("-----第一小题答案：------")
/* 第一小题：db.dept.aggregate(
 [
{$unwind: "$emp" } ,
{$group:
   { _id: "$dname",
     count: { "$sum": 1 }
   }
}
   ]
)  */
pipe := c.Pipe([]bson.M{{"$unwind": "$emp"}, {"$group": bson.M{"_id": "$dname", "count": bson.M{"$sum": 1}}}})
result := Depta{}
iter := pipe.Iter()
var i int
fmt.Printf("%2s%16s%8s\n", "序号", "部门名称", "雇员数量")
for iter.Next(&result) {
i = i + 1
fmt.Printf("%4d%20s%10d\n", i, result.Id, result.Count)
}


/*第二小题： db.dept.aggregate(
  { $unwind : "$emp" },
  { $project : {
_id : 0,
ename : "$emp.ename" ,
sal : "$emp.sal"
   }},


   { $sort : { "sal" : -1 } },
   { $limit : 3 }
); */
fmt.Println("\n\n-----第二小题答案：------")
pipe = c.Pipe([]bson.M{{"$unwind": "$emp"}, {"$project": bson.M{"_id": 0, "ename": "$emp.ename", "sal": "$emp.sal"}}, {"$sort": bson.M{"sal": -1}}, {"$limit": 3}})
iter = pipe.Iter()
i = 0
fmt.Printf("%2s%16s%8s\n", "序号", "雇员姓名", "薪水")
for iter.Next(&result) {
i = i + 1
fmt.Printf("%4d%20s%10d\n", i, result.Ename, result.Sal)
}


/*第三小题：  db.dept.aggregate(
 {$unwind : "$emp" },


 { $project : {
   ename : "$emp.ename",
   sal : "$emp.sal",
   mgrsal : "$emp.mgr.sal",
   subsal : {$subtract : ["$emp.sal",  "$emp.mgr.sal"]},
   _id : 0
 }}
 ,{$match : {"subsal" : {$gt : 0} } }
); */
fmt.Println("\n\n-----第三小题答案：------")


pipe = c.Pipe([]bson.M{{"$unwind": "$emp"}, {"$project": bson.M{"_id": 0, "ename": "$emp.ename", "sal": "$emp.sal", "mgrsal": "$emp.mgr.sal", "subsal": bson.M{"$subtract": [2]string{"$emp.sal", "$emp.mgr.sal"}}}}, {"$match": bson.M{"subsal": bson.M{"$gt": 0}}}})
iter = pipe.Iter()
i = 0
fmt.Printf("%2s%16s%8s%8s\n", "序号", "雇员姓名", "薪水", "上级薪水")
for iter.Next(&result) {
i = i + 1
fmt.Printf("%4d%20s%10d%10d\n", i, result.Ename, result.Sal, result.Mgrsal)
}


/*第四小题：  db.dept.aggregate(
   {$unwind : "$emp" },
   {$group : {_id : "$dname", averageScore: {$avg:"$emp.sal"} , totalPop : { $sum : "$emp.sal" }, countPop : { $sum : 1 } } }
)
注解：因为 aggregate 不能完成后续求平均后再比较的操作, 所以程序处理求公司平均数 与 比较大小
*/
fmt.Println("\n\n-----第四小题答案：------")


pipe = c.Pipe([]bson.M{{"$unwind": "$emp"}, {"$group": bson.M{"_id": "$dname", "davgsal": bson.M{"$avg": "$emp.sal"}, "dsumsal": bson.M{"$sum": "$emp.sal"}, "dcount": bson.M{"$sum": 1}}}})
iter = pipe.Iter()


mySlice := make([]Depta, 0, 10)


var dsum int
var dcount int
for iter.Next(&result) {
dsum = dsum + result.Dsumsal
dcount = dcount + result.Dcount
mySlice = append(mySlice, result)
}


davg := dsum / dcount
fmt.Printf("%2s%16s%8s%8s\n", "序号", "部门名称", "部门平均", "公司平均")
for i, v := range mySlice {
if v.Davgsal > davg {
fmt.Printf("%4d%20s%10d%10d\n", i, v.Id, v.Davgsal, davg)
}
}
}

---