# Import system modules
import arcpy
# Set the workspace
arcpy.env.workspace = "C:/Temp/test"
# Make a layer from the feature class
arcpy.MakeFeatureLayer_management("test.dbf", "test_lyr")
# Selected features which have a ID = 1
arcpy.SelectLayerByAttribute_management("test_lyr", "NEW_SELECTION", ' "ID" = 1 ')
#Calculate field
arcpy.CalculateField_management("test_lyr", "FIELD2", '!FIELD1!', "PYTHON_9.3")