topic Re: Search Cursor in Python Questions

Search Cursor

jaykapalczynski — Sat, 11 Dec 2021 20:56:40 GMT

Trying to figure out what the class_field variable is in this query

fc is the Feature Class
Class_field is WHAT?
name_field is the field value?

import arcpy

fc = 'c:/base/data.gdb/roads'
class_field = 'Road Class'
name_field = 'Name'

# Create an expression with proper delimiters
expression = arcpy.AddFieldDelimiters(fc, name_field) + ' = 2'

# Create a search cursor using an SQL expression
with arcpy.da.SearchCursor(fc, [class_field, name_field],
                           where_clause=expression) as cursor:
    for row in cursor:
        # Print the name of the residential road
        print(row[1])‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Search Cursor

jaykapalczynski — Fri, 18 Nov 2016 20:06:26 GMT

would it be easier to have a Search Cursor and WHERE clause using sql_clause?

Re: Search Cursor

MitchHolley1 — Fri, 18 Nov 2016 20:06:36 GMT

Please read up on cursors:

SearchCursor—Data Access module | ArcGIS for Desktop

Re: Search Cursor

jaykapalczynski — Fri, 18 Nov 2016 20:07:19 GMT

I want to search a FC where 'Field1 = No' or 'Field2 = no'

Re: Search Cursor

jaykapalczynski — Fri, 18 Nov 2016 20:09:37 GMT

yea thats where I got to example from...what the heck is class_field varaible?

Re: Search Cursor

jaykapalczynski — Fri, 18 Nov 2016 20:10:22 GMT

ooooh....I think its looking at 2 fields and not 1 is that right?

Re: Search Cursor

MitchHolley1 — Fri, 18 Nov 2016 20:11:01 GMT

yes

Re: Search Cursor

jaykapalczynski — Fri, 18 Nov 2016 20:12:27 GMT

But what If I wanted classfield=Yes and name_field=No

Re: Search Cursor

DanPatterson_Retired — Fri, 18 Nov 2016 20:16:14 GMT

good to bookmark ... What is ArcPy?—Help | ArcGIS for Desktop ....

Re: Search Cursor

RebeccaStrauch__GISP — Fri, 18 Nov 2016 20:21:52 GMT

So, I might be missing something here, but don't you want to print row[0] ?

Re: Search Cursor

jaykapalczynski — Fri, 18 Nov 2016 20:24:13 GMT

this example right from ESRI examples Example 4 here:

SearchCursor—Data Access module | ArcGIS for Desktop

Re: Search Cursor

BlakeTerhune — Fri, 18 Nov 2016 20:32:41 GMT

You need to keep reading the documentation for cursors. There's a where_clause parameter where you can specify that stuff when you create the cursor.

Re: Search Cursor

jaykapalczynski — Fri, 18 Nov 2016 20:33:38 GMT

That was just the example I was referencing....I am trying to build a query that will search at a SDE FC Where Field1 = No or FIeld2 = Yes

Re: Search Cursor

RebeccaStrauch__GISP — Fri, 18 Nov 2016 20:36:53 GMT

Prints name of the residential road

Yes, so the sample us printing the value of the field "Name". I thought you wanted to print out the value of the class_field field (that is the road class field) which should be row[0]

which field are you wanting to print?

Re: Search Cursor

RebeccaStrauch__GISP — Fri, 18 Nov 2016 20:39:42 GMT

Have you printed out your expression to make sure it is building correctly? Have you tried to test to make sure it works manually and to make sure there are records being returned? Maybe your return set is null/empty?

edit: btw, it might be better to include the code you are actaully testing v's just a couple of the example in the help. Might be something others can see and test in that.

Re: Search Cursor

jaykapalczynski — Sat, 11 Dec 2021 20:56:42 GMT

I now started using this example: not sure if I use a WHERE clause or sql_clause....very new to this so please forgive my ignorance.

But need to insert a WHERE clause : safteysign = Yes OR regulations = No

import arcpy

arcpy.env.workspace = "C:\\Users\\xxx\\AppData\\Roaming\ESRI\\Desktop10.4\\ArcCatalog\\xxx@xx.sde"

fc = "Inspection"

fields = ['safteysign', 'regulations']

# Use ORDER BY sql clause to sort field values
for row in arcpy.da.SearchCursor(
        fc, fields, sql_clause=(None, 'regulations')):
    print('{0}, {1}'.format(row[0], row[1]))‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Search Cursor

BlakeTerhune — Fri, 18 Nov 2016 20:49:50 GMT

Example 5B and example 6 in the help documentation show code using the sql_clause parameter. Read the description of the parameters for more detailed information about what each does. Think of a where_clause like a definition query or select by attributes. sql_clause is the extra SQL stuff you can't do in a definition query. In your case, you would just need to use a where_clause.

Re: Search Cursor

RebeccaStrauch__GISP — Fri, 18 Nov 2016 20:52:17 GMT

I think you want to look at sample 5b, and then take at look at SQL reference for query expressions used in ArcGIS—ArcGIS Pro | ArcGIS for Desktop For getting the SQL query set up correctly. AgainI try to build it in Python and pring it out, but also test to nsi sure it is working.

btw, your help doc was pointing to Pro..so mind us too...nit sure if you are using Pro or Desktop, or if the help us much different between the two. Just epwanted to point that out .

Re: Search Cursor

jaykapalczynski — Fri, 18 Nov 2016 21:10:38 GMT

Thank you all very much for the help...

getting confused....Blake saying to use Where Clause in ex 4? and you saying use 5b with sql_clause...

Re: Search Cursor

jaykapalczynski — Sat, 11 Dec 2021 20:56:45 GMT

Trying this

import arcpy

arcpy.env.workspace = "C:\\Users\\xx\\AppData\\Roaming\ESRI\\Desktop10.4\\ArcCatalog\\xx@xx.sde"

fc = "Inspection_2"

class_field = 'regulations'
name_field = 'region_1'

# Create an expression with proper delimiters
expression = u'{} = No'.format(arcpy.AddFieldDelimiters(fc, class_field))

# Create a search cursor using an SQL expression
with arcpy.da.SearchCursor(fc, [class_field, name_field],
                           where_clause=expression) as cursor:
    for row in cursor:
        # Print the name of the residential road
        print('{0}, {1}'.format(row[0], row[1]))‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Get this error:

Traceback (most recent call last):
File "C:\Users\adminjk\Desktop\PythonSync\Python Scripts\SearchCursor2.py", line 16, in <module>
for row in cursor:
RuntimeError: Attribute column not found [42S22:[Microsoft][SQL Server Native Client 11.0][SQL Server]Invalid column name 'No'.] [DGIF_TEST.DBO.Inspection_2]