OGR Datasource --> ExecuteSQL returns wrong feature

[mjigmond]

The following script returns the wrong feature using ExecuteSQL.

#!/usr/bin/python

from osgeo import ogr
import sys, math, time, os
       
aquifer = '/data/romania/judeteEPSG3844.shp'
aqDS = ogr.Open(aquifer)
sql = 'select * from judeteEPSG3844 where DENJUD = "CLUJ"'
aqLayer = aqDS.ExecuteSQL(sql)
feat = aqLayer.GetFeature(0)
print aqLayer.GetFeatureCount()
print feat.GetField('DENJUD')
aqDS.ReleaseResultSet(aqLayer)

Result of print statements:

1
TELEORMAN

Expected result:

1
CLUJ

I also tried a different SQL statement:

sql = 'select * from judeteEPSG3844 where DENJUD like "CLUJ"'

with the same wrong result.

Sample shapefile attached.

-marius

[mjigmond]

I had to select a subset of the original shapefile due to size restrictions.

[warmerdam]

The problem is the use of GetFeature(0) instead of GetNextFeature().

ExecuteSQL() returns a layer which can be iterated over to fetch the matching results. But you cannot expect them to be renumbered with fid's starting at zero.

In the case of the OGR implementation GetFeature() on the ExecuteSQL() layer is basically processing a feature from the underlying layer with that FID if you request things by fid.

Just change:

feat = aqLayer.GetFeature(0)

to

feature = aqLayer.GetNextFeature()