code: func FindOnUpdateCols(cols []*Column) []*Column {
  	var rcols []*Column
  	for _, col := range cols {
  		if mysql.HasOnUpdateNowFlag(col.Flag) {
  			rcols = append(rcols, col)
  		}
  	}
  
  	return rcols
  }
docs: // FindOnUpdateCols finds columns which have OnUpdateNow flag.