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I am trying to create a query for the select by attribute function within a Python script.This is my current code.

    lot = '96'
    dp = 756421

    lotFile = "D:\\NCT_GIS\\DATA\\Regional_55.gdb\\Murray\\cadastre"
    arcpy.MakeFeatureLayer_management(lotFile, "lot_lyr") 
    arcpy.SelectLayerByAttribute_management("lot_lyr", "NEW_SELECTION", "\"LOTNUMBER\" = " + lot + " AND " + "\"PLANNUMBER\" = " + str(dp))

Unfortunately I cannot concatenate and integer and if I convert DP to a string then the query is invalid as the PLANNUMBER field is numeric whilst LOTNUMBER is text.

Does anyone know how to get the variables into the query properly so that I can input any lot and dp as this will eventually become an addin where users can specify which land parcel they are interested in.

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I think this should work ... I prefer to use combinations of single and double quotes rather than backslashes to escape.

arcpy.SelectLayerByAttribute_management("lot_lyr", "NEW_SELECTION", '"LOTNUMBER" = ' + "'" + lot + "'" + ' AND "PLANNUMBER" = ' + str(dp))

Note that lot is input as a string so can be used as is, but dp which is an integer needs an str function.

  • Unfortunately not. It is giving the "cannot concatenate str and int" error. – user25074 Feb 5 '14 at 23:17
  • set dp = '756421' so it will be a string (I edited @PolyGeo's post--oop s/he beat me to it.). – Roland Feb 5 '14 at 23:19
  • Tried that but as the field PLANNUMBER is not text, the query is invalid. I somehow need to be able to have a number in this query string. – user25074 Feb 5 '14 at 23:22
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Python's format string function (along with triple-quoted strings) is an elegant way to do this:

lot = '96'
dp = 756421

lotFile = "D:\\NCT_GIS\\DATA\\Regional_55.gdb\\Murray\\cadastre"
query_str = """ "LOTNUMBER" = '{0}' AND "PLANNUMBER" = {1} """.format(lot, dp)
arcpy.MakeFeatureLayer_management(lotFile, "lot_lyr", query_str)

Format will string-ify whatever variables you add as arguments and insert them into the spot occupied by {i}, where i is the position of a particular argument in the list of arguments.

Triple-quoting the entire query string allows you to use both double and single quotes without escaping either one.

The two together allow for a highly readable query string, not broken up into a bunch of different parts that are concatenated with +.

One last note: arcpy.MakeFeatureLayer_management() has an optional 3rd argument that allows you to specify a query, thus eliminating the need for the subsequent call to arcpy.SelectLayerByAttribute_management().

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