import (
    "database/sql"
    "fmt"
    _"github.com/go-sql-driver/mysql"
)


func main() {
    db, err := sql.Open("mysql", "root:0314@tcp(127.0.0.1:3306)/golang_test?charset=utf8")
    checkErr(err)
    defer db.Close()
    // insert(db)
    // query(db)
    // update(db)
    // delete(db)
}

// insert
func insert(db *sql.DB)  {
    stmt, err := db.Prepare("INSERT user (name, age) values (?,?)")
    checkErr(err)
    res, err := stmt.Exec("Eric", 22)
    checkErr(err)
    id, err := res.LastInsertId()
    checkErr(err)
    fmt.Printf("insert id=%d\n", id)
}

// query
func query(db *sql.DB)  {
    rows, err := db.Query("SELECT * FROM user")
    checkErr(err)
    // 列，字段名
    columns, err:= rows.Columns()
    checkErr(err)
    scanArgs := make([]interface{}, len(columns))
    values := make([]interface{}, len(columns))
    for i := range values {
        scanArgs[i] = &values[i]
    }
    for rows.Next() {
        err = rows.Scan(scanArgs...)
        checkErr(err)
        // 行，记录
        record := make(map[string]string)
        for i, col := range values {
            if col != nil {
                record[columns[i]] = string(col.([]byte))
            }
            fmt.Println(record)
        }
    }
}

// update
func update(db *sql.DB) {
    stmt, err := db.Prepare("UPDATE user SET name=?,age=? WHERE id=?")
    checkErr(err)
    res, err := stmt.Exec("Rose", 21, 1)
    checkErr(err)
    num, err := res.RowsAffected()
    fmt.Printf("affected：%d\n", num)
}

// delete
func delete(db *sql.DB) {
    stmt, err := db.Prepare("DELETE FROM user WHERE id=?")
    checkErr(err)
    res, err := stmt.Exec(1)
    checkErr(err)
    num, err := res.RowsAffected()
    fmt.Printf("affected：%d\n", num)
}

func checkErr(err error) {
    if err != nil {
        panic(err)
    }
}