Using DROP is more convenient to use than SELECT. For example, to increase peformance, use DROP to remove unused columns after running JOIN statements. If you remove an attibute in the unified dataset with DROP, it is then populated with nulls.

Syntax

DROP <col1>, <col2>, ...
This statement removes all of the specified columns from the input dataset.

DROP behaves in the following ways:

• It removes a column only if the name you specified exists in the dataset.
• It does not change the ordering of remaining columns.
• If a column to be dropped duplicates another column, Tamr issues an error that “<col> is already being dropped” and removes both columns.
• DROP is not a reserved word. You can use it as the name of an attribute or a dataset.

Examples

DROP column_one;
DROP column_two, column_three, column_four;