Arcpy search cursor and update cursor to write values from table A to table B

Question

I'm a python beginner.

I`m working with ArcGIS 10.2.2 and IDLE Python 2.7.5

I have two tables, table A (top) and table B.

I need to read the attributes for the A-table fields for the selected record and write the fields and their attributes to all rows of the B table. I need the same attribute information for each row the fields.

enter image description here

I'm working with something like this

 with arcpy.da.UpdateCursor(fc2, field3) as cursor:
 for row in cursor:
 row[0] = 'Q'
 cursor.updateRow(row)
 with arcpy.da.UpdateCursor(fc2, field4) as ucursor:
 with arcpy.da.SearchCursor(fc2, field5) as scursor:
 for srow in scursor:
 sval = srow[0]
 urow = ucursor.next()
 urow[0] = "0" + sval.replace("-", "")
 ucursor.updateRow(urow)

• Erica: Possible duplicate of Getting values from attribute table and inserting another table using ArcPy?
• jbchurchill: Write values based on what? do you need to match values in table b or just create b as a copy of a?
• user63964: I need an exact copy of A table (for the seleted record) for both of B's records. I've comptely read the cursor help docs and they don't have the syntax I need I'm working with something like this but it only works for two tables that have equal numbers of records and fields:

Answer 1

I have a function I call all the time for doing this, but first, you'll need a common field to join by. From the screenshot, looks like you have a one to many relationship between the fields with several road names ('{DEER HOLLOW WAY}{HUNTERS GLEN WAY}{HUNTERS GLEN WAY}') and those with single field names ('DEER HOLLOW WAY'). You'll want to make a field that you can use to match to the records in the second table. You may want to separate this out to a 1 to 1 relationship in a new table like this:

import os
import arcpy
def flattenTable(table, new_fc, read_field='STNAMES', new_field='JOIN_NAMES'):
 # make a copy of schema
 desc = arcpy.Describe(table)
 where = '{} < 0'.format(arcpy.AddFieldDelimiters(table, desc.OIDFieldName))
 path, name = os.path.split(new_fc)
 arcpy.conversion.FeatureClassToFeatureClass(table, path, name, where)
 # add new field
 fields = ['SHAPE@'] + [f.name for f in arcpy.ListFields(table) if f.type not in ('OID','Geometry')]
 f_index = fields.index(read_field)
 arcpy.management.AddField(new_fc, new_field, 'TEXT', field_length=100)
 # search and insert cursors
 used = []
 with arcpy.da.InsertCursor(new_fc, fields + [new_field]) as irows:
 with arcpy.da.SearchCursor(table, fields) as rows:
 for r in rows:
 st_names = set(filter(None, map(lambda x: x.strip('}'), r[f_index].split('{'))))
 # make overlapping features to flat 1M to 1 to 1 relationship
 for st in st_names:
 if st not in used:
 irows.insertRow(r + (st,))
 used += list(st_names) # supress duplicates
 return new_fc
if __name__ == '__main__':
 table = r'C:\Path\to_your\create_position.shp'
 new_fc = r'C:\Path\to_your\create_position_1to1.shp'
 # change field variables if necessary
 # run it
 flattenTable(table, new_fc) #optional args for field names can be added

And finally, after you have added a common "join_field", you can call this function to add the fields. Be sure to change the variables under the __main__ block appropriately.

import arcpy
import os
FIELD_TYPES = {
 'Date':'DATE',
 'String':'TEXT',
 'Single':'FLOAT',
 'Double':'DOUBLE',
 'SmallInteger':'SHORT',
 'Integer':'LONG',
 'GUID':'GUID',
 'Raster':'RASTER'
 }
def CopyFields(source_table, in_field, join_table, join_key, join_values=[]):
 """
 Copies field(s) from one table to another
 Required:
 source_table -- table in which to add new fields
 in_field -- a field that has common values to a field in the join_table.
 think of this as a "join_field"
 join_table -- table with fields to add to source_table
 join_key -- field to match values of the "in_field"
 join_values -- fields to add to source_table (list)
 """
 def Message(msg):
 print msg
 arcpy.AddMessage(msg)
 # Get Catalog path (for feature layers and table views)
 cat_path = arcpy.Describe(source_table).catalogPath
 # Find out if source table is NULLABLE
 if not os.path.splitext(cat_path)[1] in ['.dbf','.shp']:
 nullable = 'NULLABLE'
 else:
 nullable = 'NON_NULLABLE'
 # Add fields to be copied
 update_fields = []
 join_list = [f for f in arcpy.ListFields(join_table)
 if f.type not in('OID', 'Geometry')]
 for field in join_list:
 ftype = field.type
 name = field.name
 length = field.length
 pres = field.precision
 scale = field.scale
 alias = field.aliasName
 domain = field.domain
 for fldb in join_values:
 if fldb == name:
 arcpy.AddField_management(source_table,name,FIELD_TYPES[ftype], pres, scale, length, alias, nullable, '', domain)
 Message("Added '%s' field to \"%s\"" %(name, os.path.basename(source_table)))
 update_fields.insert(join_values.index(fldb), name.encode('utf-8'))
 # update new fields
 #
 # Create Dictionary
 with arcpy.da.SearchCursor(join_table, [join_key] + join_values) as srows:
 path_dict = {r[0]: r[1:] for r in srows}
 # Update Cursor
 with arcpy.da.UpdateCursor(source_table, [in_field] + update_fields) as urows:
 for row in urows:
 if row[0] in path_dict:
 try:
 row[1:] = path_dict[row[0]]
 urows.updateRow(row)
 except:
 continue
 Message('Fields in "%s" updated successfully' %(os.path.basename(source_table)))
 return update_fields
if __name__ == '__main__':
 target_table = r'C:\Path\to_your\targetTable.shp'
 target_join_field = 'SOME_FIELD' # need to calculate this
 join_table = r'C:\Path\to_your\joinTable.shp'
 join_field = 'SOME_FIELD' # need to calculate this
 add_fields = ['QUADNAME', 'MAPNUM', 'EAM_STATUS', 'EAM_POSITION_ID'] #fields from join table to add
 # run it
 CopyFields(target_table, target_join_field, join_table, join_field, add_fields)