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Creating Tables
In the last installment we explored the many to many relationships that exist between our various table. At that point we had not yet created the tables. This article will deal with the nuts and bolts of actually creating a table.
A word about names
The names you use when you create your database objects are important and should follow certain guidelines. Access reserves certain words for its own use. Logically these words are known as reserved words. Unfortunately some of these words are the first that comes to mind when you are trying to name fields for example. In this article I discussed at a conceptual lever, the tables we need in the Ice Cream Parlour database. If you look back to that article you will see names like ‘Name”, “Description”, and “Type”. These words all have special meaning within Access and should not be used to name Access objects.
So you will notice that the field names in the relationship diagrams in my last article are different from those I used in the conceptual diagrams. So, for example I have a field ‘strSundaeName’ rather than simply ‘Name’. What about the ‘str.’ That part of the name comes from a convention I follow to add a prefix to the name that indicates the datatype of the field. Many Access developers do not use prefixes for field names. So SundaeName would be perfectly acceptable and, in fact, preferred by many developers.
On the other hand, many developers do follow a naming convention that prefixes the names of Access objects like tables, queries, forms and reports, with three characters to signify the type of object to which the name pertains. So, for example, the Sundaes table is actually called ‘tblSundaes’.
Notice also that tables are usually plural. That is because the table contains records where each record is one example (or instance) of the subject of the table. So, tblSundaes has fields with names like strSundaeName (or SundaeName, if you prefer.)
Creating a table
There are several ways to create a table in Access. Although I don’t recommend it, you can design a table by entering data into a datasheet. Access will determine the data type for each field based on the data you enter. And unless you are careful to name each field, Access will assign such helpful field names as Field1, Field2, etc.
In Access versions prior to 2007 there are table creation wizards and in 2007 there are table templates to help you out. Unfortunately, tables created by wizards or from Access 2007 templates have field names that do not follow accepted naming standards. They include spaces in the field names. Now, while this may seem perfectly natural to you if you are an Access beginner, those spaces will come back to haunt you when you decide to enhance your work using advanced features like Visual Basic for Applications (VBA).
I prefer to create all tables using the Table Design View. Before we go there, however, we should map out the fields we will need and determine what their respective data types should be. For the sake of illustration I am going to deal with creating one of the tables we have decided we need. If you are following along and creating your own ice cream parlour database, the best way for you to learn will be for you to create the other tables on your own. I will be providing a link to my version of the database with all tables created.
Before we look at the table designer, let’s summarize the information we will need for each table. I am indicating two possible names for each field. The first name follows the naming convention I prefer to use. The second is a valid name in a format that omits the data type prefix. Whichever style you choose, it is important to be consistent throughout the database.
Sundaes - tblSundaes
attribute | field name | alternate name | data type | data size | notes |
Primary Key | idsSundae | SundaeID | Autonumber | long integer | |
Name | strSundaeName | SundaeName | Text | 25 |
Dishes - tblDishes
attribute | field name | alternate name | data type | data size | notes |
Primary Key | idsDish | DishID | Autonumber | long integer | |
Name | strDishName | DishName | Text | 25 | |
Type | lngDishType | DishType | Number | long integer | foreign key – used to find the dish type description in the types lookup table |
Sizes - tblSizes
attribute | field name | alternate name | data type | data size | notes |
Primary Key | idsSize | SizeID | Autonumber | long integer | |
Name | strSizeName | SizeName | Text | 25 | |
Type | lngSizeType | SizeType | Number | long integer | foreign key – used to find the dish type description in the types lookup table |
Flavors - tblFlavors
attribute | field name | alternate name | data type | data size | notes |
Primary Key | idsFlavor | FlavorID | Autonumber | long integer | |
Name | strFlavorName | FlavorName | Text | 25 |
Ingredients - tblIngredients
attribute | field name | alternate name | data type | data size | notes |
Primary Key | idsIngredient | IngredientID | Autonumber | long integer | |
Name | strIngredientName | IngredientName | Text | 25 | |
Type | lngIngredientType | IngredientType | Number | long integer | foreign key – used to find the dish type description in the types lookup table |
Those are the basic definitions of our five central table. As already noted, we will need additional tables in the database to allow us to connect these central tables together so that the database reflects the one to many relationships between them. We will also need a lookup table for types the type descriptions used by tblDishes, tblSizes, and tblIngredients.
Coming next: Using the table designer.
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