Class SelectItem

tests/comparison/query.py:354–411

A representation of any possible expr than would be valid in SELECT [, ...] FROM ... Each SelectItem contains a ValExpr which will either be a instance of a DataType (representing a constant), a Column, or a Func. Ex: "SELECT int_col + smallint_col FROM

class SelectItem(object):
  '''A representation of any possible expr than would be valid in

     SELECT <SelectItem>[, <SelectItem>...] FROM ...

     Each SelectItem contains a ValExpr which will either be a instance of a
     DataType (representing a constant), a Column, or a Func.

     Ex: "SELECT int_col + smallint_col FROM alltypes" would have a val_expr of
         Plus(Column(<alltypes.int_col>), Column(<alltypes.smallint_col>)).

  ''&#x27;

  def __init__(self, val_expr, alias=None):
    self.val_expr = val_expr
    self.alias = alias

  @property
  def name(self):
    if self.alias:
      return self.alias
    if self.val_expr.is_col:
      return self.val_expr.name
    raise Exception('Could not determine name')

  @property
  def type(self):
    '''Returns the DataType of this item.'''
    return self.val_expr.type

  @property
  def base_type(self):
    '''Returns the base DataType of this item.'''
    return self.val_expr.base_type

  @property
  def is_basic(self):
    ''&#x27;Evaluates to True if this item is neither an aggregate nor an analytic expression.
    ''&#x27;
    return not self.is_agg and not self.is_analytic

  @property
  def is_agg(self):
    ''&#x27;Evaluates to True if this item contains an aggregate expression and does not
       contain an analytic expression. If an expression contains both an aggregate
       and an analytic, it is considered an analytic expression.
    ''&#x27;
    return not self.is_analytic and self.val_expr.contains_agg

  @property
  def is_analytic(self):
    '''Evaluates to True if this item contains an analytic expression.'''
    return self.val_expr.contains_analytic

  def __deepcopy__(self, memo):
    other = SelectItem(deepcopy(self.val_expr, memo))
    other.alias = self.alias
    return other