code: func (s *Schema) FindColumn(astCol *ast.ColumnName) (*Column, error) {
  	col, _, err := s.FindColumnAndIndex(astCol)
  	return col, err
  }
docs: // FindColumn finds an Column from schema for a ast.ColumnName. It compares the db/table/column names.
  // If there are more than one result, it will raise ambiguous error.