sql.go

	// *RawBytes in Rows.Scan), since we're about to close
	// the Rows in our defer, when we return from this function.
	// the contract with the driver.Next(...) interface is that it
	// can return slices into read-only temporary memory that's
	// only valid until the next Scan/Close. But the TODO is that
	// for a lot of drivers, this copy will be unnecessary. We
	// should provide an optional interface for drivers to
	// implement to say, "don't worry, the []bytes that I return
	// from Next will not be modified again." (for instance, if
	// they were obtained from the network anyway) But for now we
	// don't care.
	defer r.rows.Close()
	for _, dp := range dest {
		if _, ok := dp.(*RawBytes); ok {
			return errors.New("sql: RawBytes isn't allowed on Row.Scan")
		}
	}

	if !r.rows.Next() {
		if err := r.rows.Err(); err != nil {
			return err
		}
		return ErrNoRows
	}
	err := r.rows.Scan(dest...)
	if err != nil {
		return err
	}
	// Make sure the query can be processed to completion with no errors.
	return r.rows.Close()
}

// A Result summarizes an executed SQL command.
type Result interface {
	// LastInsertId returns the integer generated by the database
	// in response to a command. Typically this will be from an
	// "auto increment" column when inserting a new row. Not all
	// databases support this feature, and the syntax of such
	// statements varies.
	LastInsertId() (int64, error)

	// RowsAffected returns the number of rows affected by an
	// update, insert, or delete. Not every database or database
	// driver may support this.
	RowsAffected() (int64, error)
}

type driverResult struct {
	sync.Locker // the *driverConn
	resi        driver.Result
}

func (dr driverResult) LastInsertId() (int64, error) {
	dr.Lock()
	defer dr.Unlock()
	return dr.resi.LastInsertId()
}

func (dr driverResult) RowsAffected() (int64, error) {
	dr.Lock()
	defer dr.Unlock()
	return dr.resi.RowsAffected()
}

func stack() string {
	var buf [2 << 10]byte
	return string(buf[:runtime.Stack(buf[:], false)])
}

// withLock runs while holding lk.
func withLock(lk sync.Locker, fn func()) {
	lk.Lock()
	defer lk.Unlock() // in case fn panics
	fn()
}