DerivedTable

relationalai.semantics.frontend.base

DerivedTable(model: Model)

Base class for table-like query results with derived output columns.

A DerivedTable is the common base for query-like results such as Fragment and branching constructs like Match and Union.

You can iterate over a derived table or index into it to access DerivedColumn objects. Integer indexing selects by 0-based position. Name-based indexing works when the corresponding selected value was aliased (for example via Alias).

Notes

Most users should not instantiate this class directly.

Methods

.__iter__()

DerivedTable.__iter__() -> Iterator[DerivedColumn]

Return an iterator over this table’s derived output columns.

Iterating over a DerivedTable yields each column as a DerivedColumn. This is useful when you want to select all columns from a derived result.

Returns:

• Iterator[DerivedColumn] - Iterator over the derived output columns.

.__getitem__()

DerivedTable.__getitem__(index: int | str) -> DerivedColumn

Return a derived output column by position or by alias.

Integer indexing selects the 0-based output column position (for example fragment[0]). Name-based indexing (for example fragment["total"]) works when the corresponding selected value was aliased.

Parameters:

• index

  (int | str) - Column selector: a 0-based index or an output column name.

Returns:

• DerivedColumn - The selected derived output column.

Raises:

• IndexError - If index is an integer index that is out of range.
• KeyError - If index is a name that is not present.

Inheritance Hierarchy

Subclassed By

 semantics > frontend > base
├──  Fragment
├──  Match
└──  Union

Used By

 semantics > frontend > base
└──  DerivedColumn