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I have a feature (point) with a field called 'Sequence'. The values in this column range from 1 to n. I can use IQueryFilter to get the first value, 1.

                    Dim pQry As IQueryFilter = New QueryFilter
                    pQry.WhereClause = """Seq"" = 1"
                    pCursor = pFC.Search(pQry, True)
                    If TypeOf pCursor Is IFeatureCursor Then
                        pFeat = pCursor.NextFeature
                        If TypeOf pFeat Is IFeature Then
                            fStartElevation = pFeat.Value(nElevationFld)
                        End If
                    End If

I cannot figure out how to use this method to select the MAX value, since it varies across features. Is it possible? I'm thinking I just need the correct syntax. I have tried a few variations of pQry.WhereClause = """MAX""Seq""" after doing some forum reading regarding aggregate functions in ArcGIS, but I haven't found a solution that works.

If this isn't possible (I figured it should operate similarly to SQL), is there another preferable method for performing this task? I am aware of Select By Attribute, but the syntax for this is tricky (examples online do not work in Arc10) and still requires the attribute table to be read.

EDIT: Here is a working solution using @George's suggestion based on IDataStatistics. I may just turn this into a small function that takes in a Featureclass and field name for the sake of re-usability.

                    pCursor = pFC.Search(Nothing, False)
                    If TypeOf pCursor Is IFeatureCursor Then
                        Dim pData As IDataStatistics = New DataStatisticsClass
                        pData.Field = "Sequence"
                        pData.Cursor = pCursor

                        Dim pStatResults As IStatisticsResults = pData.Statistics
                        Dim intMaxSequence As Integer = pStatResults.Maximum
                    End If
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Strictly speaking of PGDB and FGDB; should be possible if you are querying "Access" personal geodatabase. File Geodatabase capabilities are very limited in this; you might have to loop through the cursor to find max, min, etc. – Jakub Jul 25 '11 at 16:24
@Jakub - I came across that somewhere while researching this question. For my purposes I have to be prepared to support all geodatabase formats - so I think the cursor option (combined with IDataStatistics) is the way to go. – Radar Jul 25 '11 at 17:18

1 Answer

up vote 7 down vote accepted

If you are only interested in the MAX value you can use the interface IDataStatistics. Using it you can get a simple statistical result, with min, max, mean, etc.

http://edndoc.esri.com/arcobjects/9.2/ComponentHelp/esriGeoDatabase/IDataStatistics_Example.htm

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Great - this is perfect. I've updated the question with a working code snippet. Thanks! – Radar Jul 25 '11 at 18:20

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