How to verify that a Query's where statement is valid

StephenLead

What are the best options to check whether a query's where statement is valid?

Some ideas are:

- use regex or otherwise write a function to manually validate the SQL. A drawback is that the syntax of the query.where statement may be Esri-specific (eg % vs * depending on the dataset type, etc). Also, this will not verify that the statement will actually work - it may be valid SQL but not applicable to this layer.

- run the query, and use the execute statement's error callback. The problem is that you won't know until afterwards whether it was a valid statement.

- use executeForIds and specify a known ID in conjunction with the error callback. The problem is that I won't know a valid ID at runtime.

- use executeForCount to return the number of records. The problem is that for a large dataset, the executeForCount still has to find all resulting features, which can take a while.

It would be nice to have another option (eg QueryTask.validate) on the QueryTask, to verify that the query.where statement is valid. Another approach could be for Esri to add an option on executeForCount to break after the first feature is found (rather than waiting until all features have been found).

Any other suggestions?

Thanks,
Steve

HaroldBostic

I still don't have a concrete example but a jumping off point would be to create a gp service that accepts your query then do something similar to this in your script http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//000v00000057000000

But instead of committing, just return true or false and possibly the error message if it was an invalid query.
Here's a resource for gp services http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/An_overview_of_geoprocessing_with_ArcGIS_Server/002v00000001000000/