Drop
DROP
removes one or more attributes. Dropped unified attributes appear as null columns when you preview.
Using DROP
can be more convenient to use than SELECT
. For example, to increase performance, use DROP
to remove unused columns after running JOIN statements. If you remove an attribute 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, a
“<col> is already being dropped”
message appears and removes both columns. DROP
is not a reserved word. You can use it as the name of an attribute or a dataset.
Important: Attempting to
DROP
thetamr_id
has no effect. If you explicitlyDROP
the requiredorigin_source_name
ororigin_entity_id
column, you must manually recreate and repopulate it. See Managing Primary Keys.
Examples
DROP column_one;
DROP column_two, column_three, column_four;
Updated about 3 years ago