Get the list of column keys:

Select the keys that have names matching a string pattern:

Select the keys obeying a criterion function:

Get the column keys of a Tabular object:

Get the column keys of a Dataset object:

Get the keys of a list of associations:

ColumnKeys gives the unsorted union of the keys of the associations:

The result is also consistent with the corresponding Tabular object:

Get the component keys of a TimeSeries object with several components:

Those are the column keys of the corresponding Tabular object:

The component keys of a simple TimeSeries object are "Timestamp" and "Value":

The column keys of a Tabular object can be arbitrary expressions:

Take a Tabular object:

Use string patterns to select the columns whose key ends in "1":

Use a criterion function to select the keys of columns with integers:

Get the column keys for multilevel column names:

Key columns are included in the result of ColumnKeys:

For a Tabular object with unspecified column keys, ColumnKeys returns None:

Take a Tabular object of Palmer penguin data:

Create a pivot table:

Some of the column keys are ExtendedKey:

Find all column keys for "Adelie" penguins:

ColumnKeyExistsQ[tab,key] returns True if key is in the list ColumnKeys[tab]: