Golang实现mysql where in 查询

1、第一种写法

首先说一下遇到的一个问题

sql: converting argument $1 type: unsupported type []int, a slice of int

如下代码是最初遇到问题的代码

package controllers import ( "fmt"
    "github.com/astaxie/beego"
    "mypro/models"
    "strings" ) type GetMovieInfoController struct { beego.Controller } type MovieInfo struct { Id int64 Movie_name string Movie_director string } func placeholders(n int) string { var b strings.Builder for i := 0; i < n - 1; i++ { b.WriteString("?,") } if n > 0 { b.WriteString("?") } return b.String() } func (c *GetMovieInfoController) Get() { ids := []int{5,6,7} db := models.ConnectDb(); defer db.Close() query := fmt.Sprintf("select id,movie_name ,movie_director from movie_info where id in (%s)", placeholders(len(ids))) rows, err := db.Query(query,ids) fmt.Fprint(c.Ctx.ResponseWriter, rows) fmt.Fprint(c.Ctx.ResponseWriter, ids) fmt.Fprint(c.Ctx.ResponseWriter, err) }

解决方案

package controllers import ( "fmt"
    "github.com/astaxie/beego"
    "mypro/models"
    "strings" ) type GetMovieInfoController struct { beego.Controller } type MovieInfo struct { Id int64 Movie_name string Movie_director string } func placeholders(n int) string { var b strings.Builder for i := 0; i < n - 1; i++ { b.WriteString("?,") } if n > 0 { b.WriteString("?") } return b.String() } func (c *GetMovieInfoController) Get() { ids := []interface{}{5,6,7}  //这里使用interface关键字
    db := models.ConnectDb(); defer db.Close() query := fmt.Sprintf("select id,movie_name,movie_director from movie_info where id in (%s)", placeholders(len(ids))) rows, err := db.Query(query,ids...)  //加... 这里是解决了问题，可是实质性还不知道哈，基础入门阶段，之后再了解
 fmt.Fprint(c.Ctx.ResponseWriter, rows) fmt.Fprint(c.Ctx.ResponseWriter, ids) fmt.Fprint(c.Ctx.ResponseWriter, err) item := MovieInfo{} list := []MovieInfo{} for rows.Next(){ var mid int64 var movie_name, movie_director string err = rows.Scan(&mid,&movie_name,&movie_director) if err != nil { panic(err.Error()) } item.Id = mid item.Movie_name = movie_name item.Movie_director = movie_director list = append(list,item) } fmt.Fprint(c.Ctx.ResponseWriter, list) fmt.Println(list) }

 二、第二种写法

 

package controllers import ( "fmt"
    "github.com/astaxie/beego"
    "mypro/models" ) type GetMovieInfoController struct { beego.Controller } type MovieInfo struct { Id int64 Movie_name string Movie_director string } func formatids(ids []int) ([]interface{},string) { inIds := ""
    params:=make([]interface{},0) for i:=0;i<len(ids);i++{ if i==0{ inIds+="?" }else{ inIds+=",?" } params=append(params , ids[i]) } return params,inIds } func (c *GetMovieInfoController) Get() { ids := []int{8,9,10} db := models.ConnectDb(); defer db.Close() sql := "select id,movie_name,movie_director from movie_info where id in (%s)"


    params,inIds := formatids(ids) sql = fmt.Sprintf(sql ,inIds ) fmt.Fprint(c.Ctx.ResponseWriter,sql) rows,err := db.Query(sql , params...) fmt.Fprint(c.Ctx.ResponseWriter, rows) fmt.Fprint(c.Ctx.ResponseWriter, ids) fmt.Fprint(c.Ctx.ResponseWriter, err) item := MovieInfo{} list := []MovieInfo{} for rows.Next(){ var mid int64 var movie_name, movie_director string err = rows.Scan(&mid,&movie_name,&movie_director) if err != nil { panic(err.Error()) } item.Id = mid item.Movie_name = movie_name item.Movie_director = movie_director list = append(list,item) } fmt.Fprint(c.Ctx.ResponseWriter, list) fmt.Println(list) }

 3、第三种写法

func (c *GetMovieInfoController) Get() { ids := []string{"8", "9", "10"} db := models.ConnectDb(); defer db.Close() idStr := strings.Join(ids, "','") fmt.Println(idStr) sqlText := "select id,movie_name,movie_director from movie_info where id in ('%s')" sqlText = fmt.Sprintf(sqlText, idStr) rows,err := db.Query(sqlText) } 

 

//sql
select id,movie_name,movie_director  from movie_info where id in  ('8','9','10')