sql - 如何显示查询结果计数

Question

我正在开发一个 RESTful API 项目，我遇到了一个问题，我的代码可以用 gorm 查询，我的查询是这样的 countSequenceId := db.Debug().Raw("SELECT COUNT (*) FROM SMSBlast2").扫描(&smsblast1)。我的结果是 [1 rows affected or returned]，这意味着成功计算了我在数据库中的所有行，但我想显示结果，如 result count = 10，但是如何呢？

 package main

import (
    "encoding/json"
    "fmt"
    "github.com/gorilla/mux"
    "github.com/jinzhu/gorm"
    _ "github.com/jinzhu/gorm/dialects/mssql"
    "log"
    "net/http"
    "strconv"
    "time"
)

type SMSBlast struct {
    SequenceID   int `gorm:"primary_key";column:"SequenceID"`
    MobilePhone string `gorm:"column:MobilePhone"`
    Output  string  `gorm:"column:Output"`
    WillBeSentDate *time.Time `gorm:"column:WillBeSentDate"`
    SentDate *time.Time `gorm:"column:SentDate"`
    Status *string `gorm:"column:Status"`
    DtmUpd time.Time `gorm:"column:DtmUpd"`
}

func (SMSBlast) TableName() string {
    return "SMSBlast2"
}

func allSMSBlasts(w http.ResponseWriter, r *http.Request){
    db, err := gorm.Open("mssql", "sqlserver://sa:@localhost:1433?database=CONFINS")
    if err != nil{
        panic("failed to connect database")
    }
    defer db.Close()

    var smsblasts []SMSBlast
    db.Debug().Find(&smsblasts)
    fmt.Println("{}",smsblasts)

    json.NewEncoder(w).Encode(smsblasts)
}

func insertSMSBlast(w http.ResponseWriter, r *http.Request){
    fmt.Println("New Insert Created")

    db, err := gorm.Open("mssql", "sqlserver://sa:@localhost:1433?database=CONFINS")
    if err != nil{
        panic("failed to connect database")
    }
    defer db.Close()

    vars := mux.Vars(r)
    mobilephone := vars["mobilephone"]
    output := vars["output"]

    var(
        smsblast1 SMSBlast
    )


    countSequenceId := db.Debug().Raw("SELECT COUNT (*) FROM SMSBlast2").Scan(&smsblast1)
    fmt.Println(countSequenceId)


    msg, err :=  json.Marshal(countSequenceId)
    if err != nil{
        fmt.Println(err.Error())
    }



    sequenceid1,_ := strconv.Atoi(string(msg))
    fmt.Println("SequenceID : " , sequenceid1)

    smsblasts := SMSBlast{SequenceID: sequenceid1,MobilePhone: mobilephone,Output:output, DtmUpd: time.Now()}
    prindata := db.Create(&smsblasts)
    fmt.Println(prindata)

func handleRequests(){
    myRouter := mux.NewRouter().StrictSlash(true)
    myRouter.HandleFunc("/smsblaststest",allSMSBlasts).Methods("POST")
    myRouter.HandleFunc("/smsblaststestInsert/{mobilephone}/{output}", insertSMSBlast).Methods("POST")
    log.Fatal(http.ListenAndServe(":8080",myRouter))

}

func main(){
    fmt.Println("SMSBLASTS ORM")
    handleRequests()
}

Answer 1

我不确定您为什么为此使用 Raw 方法，但我想指出有一个 Count 方法可以实现您想要的:http://gorm.io/docs/query.html#Count

db.Where("name = ?", "jinzhu").Or("name = ?", "jinzhu 2").Find(&users).Count(&count)
//// SELECT * from USERS WHERE name = 'jinzhu' OR name = 'jinzhu 2'; (users)
//// SELECT count(*) FROM users WHERE name = 'jinzhu' OR name = 'jinzhu 2'; (count)

db.Model(&User{}).Where("name = ?", "jinzhu").Count(&count)
//// SELECT count(*) FROM users WHERE name = 'jinzhu'; (count)

我从文档中整理了一个非常简单的示例:

package main

import (
    "fmt"

    "github.com/jinzhu/gorm"
    _ "github.com/jinzhu/gorm/dialects/sqlite"
)

type Porg struct {
    gorm.Model
    Name string
}

func main() {
    db, err := gorm.Open("sqlite3", "test.db")
    if err != nil {
        panic("failed to connect database")
    }
    defer db.Close()

    // Migrate the schema
    db.AutoMigrate(&Porg{})

    // Create
    for i := 1; i <= 100; i++ {
        db.Create(&Porg{Name: "John"})
    }

    // Read
    var porgs []Porg
    var count int
    db.Model(&porgs).Count(&count)

    fmt.Println(count)
}

输出:100

使用 Model 方法，您可以指定要查询的模型，这不会直接查询数据库。使用 db.Find(&porgs).Count(&count) 实际上会向数据库发送 2 个 SQL 查询。