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Postal codes - assess validity

GRCTools manual | Index

Purpose: to check the validity of postal codes by analysing them for correct length, correct character type, the presence of invalid characters and the presence of foreign postal codes.

image This process requires the postal code to be written in the user-specified field in the correct format and without the addition of country codes such as F-75000 or GB-W1A 4ZA. I.e. these postal codes need to be written 75000 and W1A 4ZA.

A file called PddmmyyX.DBF, where ddmmyy is the date and X is an incremented letter is created to store any records containing problem postal codes. GRC ToolsTM will tell you at the top right of the screen the name of the file created for this session:


image If you should do more than 26 runs in a single day and have thus created files ending in all letters between A and Z, A is re-used for all remaining sessions for that date.

image The PddmmyyX.DBF file is created in Visual Foxpro format. To view this file you will need Visual Foxpro or a program which can import Visual Foxpro files.

image You are required to specify the field in your database containing its unique identification code, or check the Check to use RECORD NUMBERS instead of ID box to store the record number to the file created instead of an ID. You also need to specify the names of the fields containing the company name, street address (the second line is optional) and the settlement name.


For the United Kingdom only, you have the option of allowing abbreviated forms of postal codes. In London particularly, addresses are often given with only the outward (first section) of the postal code, e.g. SW1 instead of SW1 2AB. Though these postal codes are technically incomplete, this option allows you not to mark these abbreviated postal codes as incorrect.


Some countries embrace other, smaller, countries within their postal systems (such as Switzerland with Liechtenstein, Italy with San Marino and Holy See, etc.), and the addresses from the smaller countries are often mixed up in databases of addresses from the bigger country. This process can identify these addresses and assign a new country code to them. If you choose to do so, you must specify the field which contains the country code, and the codes that you wish to use for these countries. In some cases, the countries listed are not officially in a different country. For example, the French Overseas Territories such as Guadeloupe and Martinique are constitutionally part of France; and the crown dependencies of the Channel Islands and the Isle of Man are not entirely independent, though they are not a part of The United Kingdom. They have, however, been included for completeness, as many users want to code these areas differently. If this is not the case, simply assign the same code for, for example, the Guadeloupe, as you have assigned for - in this case - France itself.


The PddmmyyX file created will contain the unique identification code of the record (or the record number if you so choose by checking the Check to use RECORD NUMBERS instead of ID box), the name of the field which was checked, the incorrect postal code, the country in which it belongs, a description of the problem, and, because this information can often give a clue to the correct postal code, the company name, address and settlement names. For example, for France:

id field_name postal code country message corr_pc corr_coun company address address_2 city
19 testfile.pc 790231 France Postal code must be 5 digits long     ... ... ... ...
38 testfile.pc 99001 France String 99 not allowed in postal code position 1            
47 testfile.pc 1043 France Postal code must be 5 digits long            
47 testfile.pc 1043 France Digit 5 in postal code must be NUMERIC            
... ... ... ... ...            

This file can then be used to correct postal codes in the original file by entering the corrected postal code and/or country code into the fields corr_pc and corr_coun and running the process Postal codes - write located. Please refer to Postal codes - write located for details