Populating a column within a ScriptEval?

[triphook]

I'm loading a number of datasets and would like to create a column each one with a unique identifier. This code fails:

Load * Extension GeoOperations.ScriptEval('
SELECT geometry as Geometry, field1 as Field1, "table1" as Table_ID

FROM

Load()
DATASOURCE dataset GEOFILE url="my_url", type="esriJson", expectedGeomType="point", crs="auto"
');

While the same syntax (SELECT  "table1" as Table_ID) works in normal usage.