一.下载依赖
终端中输入:
go get -u github.com/go-sql-driver/mysql
导入包
import ("database/sql"_ "github.com/go-sql-driver/mysql" )
二.案例
package main//go get-u github.com/go-sql-driver/mysql 获取驱动
import ("database/sql""fmt"_ "github.com/go-sql-driver/mysql"
)var db *sql.DB
//根据数据库表中,有属性id,name,age,且id为插入时,自增1
var usergroup map[int]user = make(map[int]user, 100)type user struct {id intname stringage int
}func initDB() (err error) {//连接数据库dsn := "root:9826942694yzy@tcp(127.0.0.1:3306)/sql_test"db, err = sql.Open("mysql", dsn) //dsn格式不对这里会报错if err != nil {fmt.Printf("dsn: %s invaid! err:%v\n", dsn, err)return err}//判断一下是否连接成功err = db.Ping()if err != nil {fmt.Printf("open %s failed! err:%v\n", dsn, err)return err} else {fmt.Printf("open %s success!\n", dsn)}//设置数据库连接池的最大连接数,根据业务调整db.SetMaxOpenConns(10)db.SetMaxIdleConns(5) //最大闲置连接数return nil
}// 输入id,返回对应的user信息 查询单条记录
func queryOne(id int) (u user, err error) {//查询单条语句sqlstr := "select * from user where id=?" //?为占位符,在Query的时候可以用后续的参数进行填充rowObj := db.QueryRow(sqlstr, id) //从数据库连接池中拿去一个连接去进行查询//得到了rowObj必须调用Scan方法,因为该方法会释放数据库连接,把连接放回连接池,否则连接池最大连接用完,则会影响后续连接查询rowObj.Scan(&u.id, &u.name, &u.age)if rowObj == nil {fmt.Printf("query failed,err:%v\n", err)return u, err}return u, nil
}// 查询多行 读取到map中
func query() (err error) {sqlstr := "select * from user"rows, err := db.Query(sqlstr)if err != nil {fmt.Printf("query failed,err:%v\n", err)return}//记得关闭,放回连接池defer rows.Close()var u user//用一个for循环,把每次读到的行信息,存放到全局变量usergroup中,达到程序启动初始化的效果for rows.Next() {err = rows.Scan(&u.id, &u.name, &u.age)if err != nil {fmt.Printf("scan failed,err:%v\n", err)return}usergroup[u.id] = u}return nil
}// 插入一条学生数据,并且更新map id是主码,
//实际插入学生数据的时候,并不知道数据库中学号应该分配多少,所以在插入后得到返回的id,再更新map
func insert(u user) (id int64, err error) {sqlstr := "insert into user(name,age) values(?,?)"var res sql.Result//执行该语句res, err = db.Exec(sqlstr, u.name, u.age)if err != nil {fmt.Printf("insert failed,err:%v\n", err)return}//拿到插入的id,返回id, err = res.LastInsertId()if err != nil {fmt.Printf("insert failed,err:%v\n", err)return}return id, nil
}//删除指定id的user,实际上最好判断一下是否存在map中,这里就先不写了
func deleteUser(id int) (err error) {sqlstr := "delete from user where id=?"_, err = db.Exec(sqlstr, id)if err != nil {fmt.Printf("delete failed,err:%v\n", err)return err}delete(usergroup, id)return nil
}// 查询单条语句
func test01() {//查询学号为1的学生信息u, err := queryOne(1)if err != nil {fmt.Printf("query failed,err:%v\n", err)return}println(u.id, u.name, u.age)}// 程序初始化时,把user表中信息全部读取到map中
func readToMap() {//从数据库中读取user放入map中err := query()if err != nil {fmt.Printf("query failed,err:%v\n", err)return}
}// 测试插入
func myInsertTest() {var u useru.age = 23u.name = "周杰伦"id, err1 := insert(u)if err1 != nil {fmt.Printf("insert failed,err:%v\n", err1)return}//说明插入成功u.id = int(id)usergroup[u.id] = u
}//遍历map
func printMap() {//遍历for _, u := range usergroup {println(u.id, u.name, u.age)}println("***************************************")
}func main() {err := initDB()defer db.Close()if err != nil {fmt.Printf("init db failed,err:%v\n", err)return}readToMap()printMap()myInsertTest()printMap()}