Okay, I’ll admit I’m a bit of a fan of the Array. You either love or hate an Array. People who dislike the Array will often opt for a Collection instead. Other languages do provide a really cool object called a Dictionary or Hash Table. This is like a Collection that behaves like a Collection combined with an Array with some extra handy methods. VBA does not have this but VBScript does provide a Dictionary object, which is cool, and we can make use of this object within our VBA environment. To build a dictionary object do the following:

Dim my_dictionary as Object
Set my_dictionary = CreateObject("Scripting.Dictionary")

Voila! We have a dictionary. What can we do with it? We can add items, check for the existence of items, return an array of keys, return an array of items, set how a dictionary compares keys and get the count and so on. An example:

‘First create the Dictionary Object
Dim my_dictionary as Object
Set my_dictionary = CreateObject("Scripting.Dictionary")

‘When adding an object or value to a dictionary you put the key first and the actual value or object second. The key is mandatory and you cannot add items without it.
my_dictionary.Add "Key 1", "Value 1"
my_dictionary.Add "Key 2", "Value 2"
my_dictionary.Add "Key 3", "Value 3"
my_dictionary.Add "Key 4", "Value 4"

So now we’ve added four values to the dictionary. Let’s do some things we cannot do cleanly or at all with a Collection. Say we want to replace "Value 3" with the name "Zebra". Too easy!

my_dictionary.Item("Key 3") = "Zebra"

You couldn’t do that with a collection! In a collection you would have to remove one item and add another, thus losing the order or your items. A dictionary behaves like an Array in this respect. What if we were not sure there was a key called "Key 3" within the dictionary and wanted to avoid an error. Again, easy, we just use the Exists method of the dictionary object:

if my_dictionary.Exists("Key 3") then
my_dictionary.Item("Key 3") = "Zebra"
else
my_dictionary.Add "Key 3", "Zebra"
end if

We might want to know how many items are in the dictionary, just use the Count method which is the same as the one in a collection.

MsgBox my_dictionary.Count

If you want to iterate through the items in a dictionary, you can’t use an integer counter as you would an Array or Collection but you can use two methods to do so:

‘You can just grab the items from the dictionary like so:
Dim items as Variant
items = my_dictionary.Items

‘Iterate through the array of items. These items can include objects aswell.
Dim separate_item as Variant
For Each separate_item in items
MsgBox separate_item
Next separate_item

‘Or you can extract the keys and iterate through the items (which is another advantage over a Collection that does not give you it’s keys or let you know what they are)
Dim keys as Variant
keys = my_dictionary.Keys

‘Iterate through the array of items. These items can include objects aswell.
Dim key as Variant
For Each key in keys
MsgBox my_dictionary.Item(key)
Next key

Too easy! To remove an item or all items you can use Remove and RemoveAll respectively:

my_dictionary.Remove("Key 2")

Or

my_dictionary.RemoveAll

These are the basics. I’ll look at the CompareMode method in un minuto. The Dictionary object is a real advantage when we need to build a Collection of Collections or a Class Collection. For example; say we had to collect data on spys and their current missions. Usually we would have to create a Class Object called Spy and hold a Private or Public Collection within the class to which we would add their missions. One class too many (A Collection is a Class)! Let’s use a Dictionary instead…

Dim my_dictionary As Object Dim missions As Collection Dim spy_name As String Dim keys, key As Variant Set my_dictionary = CreateObject("Scripting.Dictionary")

‘Add three lots of spies.
Set missions = New Collection
spy_name = "Alexander Poligraphovich"
missions.Add "Vladivostok"
missions.Add "Ukraine"
missions.Add "Beijing"
my_dictionary.Add spy_name, missions

spy_name = "Mohammed Ramadan"
Set missions = New Collection
missions.Add "Munich"
missions.Add "Tehran"
missions.Add "Sydney"
my_dictionary.Add spy_name, missions

spy_name = "Sri FitzPatrick"
Set missions = New Collection
missions.Add "Dublin"
missions.Add "San Francisco"
my_dictionary.Add spy_name, missions

keys = my_dictionary.Keys
For Each key In Keys
MsgBox key & vbCrLf & _
my_dictionary(key).item(1) & vbCrLf & _
my_dictionary(key).item(2) & vbCrLf & _
my_dictionary(key).item(3)
Next key

The CompareMode method lets you set how the dictionary compares it’s keys when looking for duplicates etc. There are four compare modes vbBinaryCompare, vbTextCompare, vbDatabaseCompare (for MS Access only) and vbUseCompareOption (which uses the setting in the Option Compare statement at the top of a module). How can we use this? Say we add two values with the Keys of monkey and MONKEY’ one in all lowercase and the other in all uppercase.

my_dictionary.Add "monkey", "Giraffe"
my_dictionary.Add "MONKEY", "Elephant"
MsgBox my_dictionary.Count

The MsgBox will show an item count of 2, because the two keys are essentially different. The dictionary is performing a binary comparison upon the keys so you can add more than one ‘monkey’ as long as they have some difference in character case. What if we wanted the word monkey in all of it’s forms to be compared by name and not content? In other words we don’t want more than one ‘monkey’ in the dictionary. We use CompareMode vbTextCompare:

my_dictionary.CompareMode = vbTextCompare
my_dictionary.Add "monkey", "Giraffe"
my_dictionary.Add "MONKEY", "Elephant"
MsgBox my_dictionary.Count

On this example we don’t even get to the Msgbox, instead we get an error stating "This Key is already associated with an element of this collection.". This stops two keys being added that have the same name. vbBinaryCompare behaves the same way as the first example does (it is the default) and vbDatabaseCompare….Well I read what it did once and never had to remember it again! You can find explanations for these, albeit very succinct, within the MS Help in Access, or better still Google it.

Hopefully this gives you an extra tool alongside the Collection or Array and some ideas on future use. A Dictionary makes code structure cleaner and more humanly understandable. This VBScript tool will really pay dividends.

Duane Hennessy Senior Software Engineer and Systems Architect. Bandicoot Software Tropical Queensland, Australia (ABN: 33 682 969 957)

Why recode the wheel? http://www.bandicootsoftware.com.au

Moderator of http://groups.yahoo.com/group/AccessDevelopers

Whether you are an experienced web programmer or a complete novice attempting to provide data interactivity with your web site, MyQSL is an easy to use and free database solution that can allow you to store and configure data to be displayed on your web site.

The best way to create and manage a MySQL database is to download an open source (free) program called PhpMyAdmin. PHPMyAdmin allows you to manage all aspects of both your database structure and data from one easy to use interface. This tool is intended to handle the administration of MySQL over the Web.

This tool provides an interface that allows you to create and drop databases, create, drop, or alter tables, delete, edit, or add fields, execute any SQL statement, manage keys on fields, manage privileges, and import and export data into various formats. That sounds like a complicated set of activities, but the easy to use graphical tools make things quite simple and easy to understand. If you make a mistake, the software even provides instructions on where you made your error.

For a complete demo see: http://www.phpmyadmin.net/phpMyAdmin/
For documentation visit: http://www.phpmyadmin.net/home_page/docs.php

Most Linux based web hosting companies provide PhpMyAdmin as a standard feature with their packages. It is also available in a “Windows” IIS version. If your hosting provider does not already have this product installed they will often install it for you, or even allow you to install it yourself. Setup is quick and easy if you follow the step-by-step installation documentation.

Step One: Creating your new database

When you log in to your PhpMyAdmin welcome page, the first step is to enter a name for your new database in a text box provided. You can name your database anything that you wish, however if you are creating the database to use with a script or software package that you purchased somewhere, the script provider will often suggest a “preferred” database name. You should always create your database using the following format:

username_ databasename
Example: myusername_mydatabase

Your complete database name should always begin with your username followed by an underscore, then followed by the database name. This allows the server to know which user is in control of the new database, and it will also provide permission to access the database to only specific users. This also allows different users on the same server to use the same name for their own database, as you did, without interfering with your data – that is helpful if more than one user on your server bought similar software for their own site. They can then also use the software providers “preferred” database name.

Step Two: Creating a table for your new database

After you have created a database, the next step is to create a table, or even multiple tables, for you to store data. A table is the part of your new database that actually stores data.

You create a table by selecting the database that you created from the drop box list of databases. Once a database is selected a new form appears and asks for you to create a new table.

You must decide what you want to name your table and enter that name into the name box. Try to choose a name that reflects the type of data that will be stored in the table, such as orders, users, or inventory.

You then must decide how many “fields” or columns of data that you want to store for each record. If you need for the table to store five (5) different items, such as username, users email address, users telephone number, users account number, and the users age, than you would need five (5) fields. Simply enter the number 5 in the appropriate box. Once you hit create, the system will create a table and will add those fields into the table for you. Don’t worry about the number of fields you might need right now, as you can always add or delete fields later.

Step Three: Defining Fields

Once you have created your table you will be prompted to tell the database what features that you want each field to have. This looks complicated, but it’s not if you select your data type from the information below. You basically have to decide between three common data types and select the best choice for storing your data. If you make a mistake you can go back and edit the field.

If the field is to be used to store numbers, here are some choices:

TINYINT – A very small integer. The signed range is -128 to 127.
SMALLINT - A small integer. The signed range is -32768 to 32767.
MEDIUMINT - A medium-size integer. The signed range is -8388608 to 8388607.
INT - A normal-size integer. The signed range is -2147483648 to 2147483647.
BIGINT – A very large integer.

Some other less common number options include:

FLOAT- A floating-point number.
DOUBLE – A double-precision floating-point number.
DECIMAL - A packed exact fixed-point number.

If the field is to be used to store text or both text and numbers combined, here are some choices:

VARCHAR is for varying characters and can be up to 255 characters in length.
TEXT is a column with a maximum length of 65,535 characters – easy to search.
BLOB is a column with a maximum length of 65,535 characters – case-sensitive.

If the field is to be used to store dates, here are some choices:

DATE - A date.
DATETIME - date and time combination.
TIMESTAMP - useful for recording the date and time of an INSERT or UPDATE operation.
TIME - A time.

Once you have selected the data type for your fileds you will need to let the system know how many characters that you will need to store in the field.

Example: if you are storing a username, you might want to select VARCHAR as your data type and allow up to 100 characters for that field. If you are creating a User Identification number you might want to select INT and allow up to six characters – that would allow you to have up to 999,999 users.

The last step to creating your data fields is to select any special attributes that you may find helpful. Some examples are:

Auto Increment: Auto-Increment fields are useful for assigning unique identification numbers for users, products, and customers, etc. By default, fields are incremented using number characters (like "1", "2").

Primary Key: The primary key is a data column that uniquely identifies a specific instance of that data. At least one of your fields must be a Primary Key. Username is an example of a good primary key. You do not want to have more than one individual having the same username.

Index Key: Allows you to speed up searches by designating a field as a preferred data source, especially when combining data from multiple tables.

Congratulations, once you have completed these steps you are ready to import data into your new database.

Don Beavers lives in Bryan/College Station, Texas and is an enterprise level PHP-MySQL programmer at both the Shopping Elf Shopping Guide and the Datavor Web Directory.