FunctionX

Tables Fundamentals

 

Introduction to Tables

 

Single-Dimensional Lists

A list is a series of items that share a certain criterion. Such items can be people names, book titles, budgets of commercial companies, etc. Such a list is also referred to as single-dimensional because all of its items belong to one particular category or series.

Suppose you have a business and you want to create a list of your customers. You can start with their names: Alex Cooks, John Hoover, Mimosette Oakley, Yitzah Shiloh, Robert McLain, Helene Brecht. The list can be visually set horizontally or vertically as follows:

Customer Name
Alex Cooks
John Hoover
Mimosette Oakley
Yitzah Shiloh
Robert McLain
Helene Brecht

Two-Dimensional Lists

As seen in the above list of customers, if you are dealing with just a simple list, it would be complete. In your business, you certainly would like to have more information than that about each customer. For example, if your business is a bank, you certainly would need to create an account for each customer. The account numbers may appear as follows: 91-205-8, 60-137-2, 44-996-4, 99-846-7, 35-702-5, 76-868-5. The list of these account numbers also can be displayed horizontally or vertically as done above:

Account Number
91-205-8
60-137-2
44-996-4
99-846-7
35-702-5
76-868-5

As you can see, this new list is made of insignificant numbers when the list is considered by itself. To make it useful, the list can be added to the earlier list vertically as follows:

Customer Name Account Number
Alex Cooks 91-205-8
John Hoover 60-137-2
Mimosette Oakley 44-996-4
Yitzah Shiloh 99-846-7
Robert McLain 35-702-5
Helene Brecht 76-868-5

A two-dimensional list of made of a series of items such that the series itself belongs to another series. The concept of a two-dimensional list is at the heart of a table: A database table is a two-dimensional list made of columns and rows. A column is a one-dimensional list whose items make up a single category of values. In our example, one category is labeled Customer Name and another category is designated as Account Number. The series of values of each category but belonging to the same row is called a record. For example, the values John Hoover and 60-137-2 belong to the same record.

 

Database Tables

Before creating a table, you should plan it: figure out what values you want to include in the table. In our example, you may want one category used for the names of customers. Another category would contain the account number for each customer. As your business becomes significant, you may need to keep a better list of your customers. For example, you can add another category for the customers' addresses. Another category could specify their work phone.

Once you have decided what the category would be made of, you can create it. In Microsoft Access, there are six main techniques you can use to either create or make a table available to your database.

Practical Learning: Introducing Tables

  1. If you want to follow, Create a new folder called Watts A Loan1
  2. Start Microsoft Access and create a blank database. Name it Watts A Loan and save it in your Watts A Loan folder
 

Creating a Microsoft Access Table

 

The Datasheet View

Creating a table in Datasheet View consists of displaying it like a spreadsheet and either entering data or changing the names of columns. To do this, if you are using Microsoft Access >= 2000, from the Tables section of the Database window, you can double-click Create Table By Entering Data. This would present you with a spreadsheet-like window.

Alternatively, and regardless of your version of MS Access, you can first display the New Table dialog box. You can get it from the main menu where you would click Insert -> Table. Y can also click the New button on the Database window while in the Tables section. Any of these two actions would display the New Table dialog box. From the New Table dialog box, you can click Datasheet View and click OK or you can double-click Datasheet View:

Once in the Datasheet View, to change the string that displays on a column header, you can double-click Field1, Field2, or any field you want, type the desired string, and press Enter. You can also right-click a column header, click Rename Column, type a string and press Enter. Alternatively, while a column has focus, on the main menu, you can click Format -> Rename Column, type a name and press Enter

Practical Learning: Creating a Table in Datasheet View

  1. If you want to follow, on the main menu, click Insert -> Table
  2. In the New Table dialog box, double-click Datasheet View
  3. As a cell is selected under the Field1 column, on the main menu, click Format -> Rename Column. Type TransactionNumber
  4. Double-click Field2 and type TransactionDate
  5. Right-click Field3 and click Rename Column. Type TransactionAmount and press Enter
  6. To save the table, press Ctrl + S
  7. On the Save As dialog box, type Transactions and press Enter
  8. When a long message box comes up, read it and press Enter
  9. Close the table

The Table Wizard

The Table Wizard is one of the most flexible means of creating a table. It presents a series of already configured columns that you can simply select from sample tables.

To start the wizard, you can display the New Table dialog box that you can get from the main menu at Insert -> Table or by clicking the New button on the Database window while in the Tables section. Any of these two actions would display the New Table dialog box

From the New Table dialog box, you can click Table Wizard and click OK or you can double-click Table Wizard.

If you are using Microsoft Access >= 2000, from the Tables section of the Database window, you can double-click Create Table By Using Wizard.

On the first page of the Table Wizard, you can first select a category either as Business or as Personal using one of the radio buttons. Once you locate the type of table that is close to the type of list you are trying to create, you can click it in the Sample Tables list box. This would display its types of items in the Sample Fields list box. From there, if you see a field you like, you can double-click it.

When creating the list, the items are added in the order they are double-clicked and you cannot change their positions using the wizard. Instead, you can insert an item under another. For example, if you click EmployeeNumber in the Fields In My New Table list and then double-click DateHired in the Sample Fields, the new field, in this case DateHired, would be added just under the one that was highlighted, in this case EmployeeNumber.

If you have added a field but don't like its name, you can change it. To do this, you can select the field in the Fields In My New Table list, click Rename Field, type the new name and press Enter.

Practical Learning: Creating a Table Using the Wizard

  1. On the main menu, click Insert -> Table. In the New Table dialog box, double-click Table Wizard
  2. In the Sample Tables, click Employees
  3. In the Sample Fields, double-click EmployeeID, EmployeeNumber, FirstName, MiddleName, LastName, Title, Address, City, StateOrProvince, PostalCode, Country, HomePhone, WorkPhone, Extension, Salary, and Notes
  4. In the Fields In My New Table list, click EmployeeID to select it
  5. In the Sample Fields, double-click DateHired
  6. In the Fields In My New Table, click StateOrProvince and click Rename Field...
  7. Delete OrProvince and press Enter
  8. In the Sample Fields, double-click DateHired
  9. In the Fields In My New Table, click PostalCode and click Rename Field...
  10. Replace Postal with ZIP to produce ZIPCode and press Enter
  11. Click Next
  12. Accept the name of the table as Employees and click Next
  13. Click Next twice and click Finish
  14. Close the table

Table Design View

Probably the best way to exercise as much control over the creation or configuration of a table is in a window called the Design View. It presents all types of options for each fields and any thing that can be done on a field.

To display the table in Design View, you can first call the New Table dialog box and then double-click Design View. If you are using Microsoft Access >= 2000, from the Tables section of the Database window, you can double-click Create Table In Design View:

While in Design View, to create a column, you can click a field under the Field Name column, type a name and press Enter. After setting the name of a field, you should specify the type of data that the cells in that column would accept or should reject. This is done by specifying its data type. The data type is selected from the Data Type column in the cell corresponding to the field name. The types available are:

Text: A Text data type allows the user to type any kind of characters or group of characters. This field can hold up to 255 characters

Memo: The Memo data type functions like the Text except that it can hold a longer text up to 64000 characters

Number: The Number data type will allow a combination of digits using 0 to 9. As you will see shortly, there are various forms of numbers. You will get to specify further number formats you need for your database

Date/Time: The Date/Time data type allows you to control data entry to some fields for recognizable date or time values. There are various formats used

Currency: The Currency data type will accept only a number in its field. That number is then converted to represent money value

AutoNumber: You use the AutoNumber data type to ask Microsoft Access to complete that field with automatically generated numbers for a field whose number you don't need to control

OLE Object: An OLE Object field allows you to include pictures, graphics, other application files (for example Microsoft Word documents or Microsoft Excel spreadsheets, etc)

Hyperlink: With the Hyperlink, you can provide a link to a file in your computer or to a web page on the Internet

The lower section of the table presents many more options for each field.

Practical Learning: Creating a Table Design View

  1. On the Database window, click Tables and and click New. In the New Table dialog box, double-click Design View
  2. Type CustomerID and press Tab
  3. In the Data Type, select AutoNumber
  4. Right-click CustomerID and click Primary Key
  5. Click the field under CustomerID. Type AccountNumber
  6. Click the field under AccountNumber. Type CustomerName and press Enter 
  7. To save the table, press Ctrl + S
  8. Type Customers and press Enter
  9. Press Ctrl + F4 to close the table
  10. Right-click Transactions table and click Design View
  11. Double-click ID to select it. Type TransactionID and press Enter
  12. Save and close the table

Table Importing

The last technique, probably the least flexible, consists of importing either a table from another application or only data you can use to create a new table. You can also import data and insert it in an existing table.

To import a table, you can first display the New Table dialog box, click Import Table and click OK, or you can double-click Import Table. Alternatively, on the main menu of Microsoft Access, you can click File -> Get External Data -> Import... Either of these actions would call the Import dialog box from where you can select the application or the database that is holding the table you want to import. After selecting the application or the database, the Import Objects dialog box would come up:

From there, you can select the category and the objects you want to import, then click OK.

After importing data, you can switch the table to Design View and change some characteristics of the fields as you see fit and as possible.

Practical Learning: Importing Data

  1. Open Notepad and type the following text (make sure you press Enter at the end of each line):
     
    "TypeOfLoan","Notes"
    "Personal","This is loan given as a cashier check to a customer who wants a cash loan"
    "Car","This loan will be processed by our partners as car dealers"
    "Boat",
    "Furniture",
    "Musical Instrument","Loan through for a customer who wants to buy (studio) equipment"
  2. Save it as TypesOfLoan.txt in a folder you can recognize, such as your My Documents, and close Notepad
  3. On the main menu of Microsoft Access, click Insert -> Table, in the New Table dialog box, click Import Table and click OK
  4. In the Import dialog box, change the Files Of Type to Text Files and locate the folder that contains the text file you saved above
  5. Click the TypesOfLoan text file and click Import
  6. In the first page of the wizard, accept that text is Delimited and click Next
  7. In the second page, accept that the Comma is used as the separator. Click the First Row Contains Field Names and click Next
  8. Accept to Store Data In A New Table and click Next
  9. Accept to Let Access Add Primary Key and click Next
  10. Accept the name of the table as TypesOfLoan and click Finish

Table Linking

Another technique used to use external data consists of linking to it instead of importing. This allows the original application to preserve its data and only make it available to your database.

To link to external data, you can first call the New Table dialog box. From there, you can click Link Table and click OK or you can double-click Link Table. Alternatively, on the main menu, you can click File -> Get External Data -> Link Tables... This would call the Link dialog box. You can then select the application that holds the data you want and click Link. You would be presented with a Link Tables dialog box:

This gives you the opportunity to select the table(s) and click OK.

When linking to an external table, since the table actually belongs to another application, file, or database, you should not change characteristics of its fields

Practical Learning: Linking to External Data

  1. If you have Microsoft Excel, open it and, in Sheet1, type the following
     
  2. Double-click Sheet1. Type LoanEvaluation and press Enter
  3. Save the spreadsheet as Evaluation in your Watts A Loan folder and close Microsoft Excel
  4. On the main menu of Microsoft Access, click Insert -> Table. In the New Table dialog box, click Link Table and click OK
  5. In the Link dialog box, change the Files Of Type to Microsoft Excel and locate your Watts A Loan folder
  6. Click Evaluation and click Link
  7. In the first page of the wizard, accept to use the LoanEvaluation worksheet and click Next
  8. In the second page, click the First Row Contains Column Headings and click Next
  9. Accept the Table Name as LoanEvaluation and click Finish
  10. When the acknowledgement comes up, click OK

A Table From a SQL Statement

You can also create a table using a SQL statement. To do this, you must first start a query as if you were creating a query. This is because Microsoft Access doesn't provide a native environment to write SQL code or put it another way, to write a SQL statement, you must open a query window.

The syntax of creating a table is

CREATE TABLE TAbleName;

The CREATE and TABLE keywords are required to indicate that you want to create a table.

Tables Relationships

Overview

Relationships allow data to flow from one table or object to another. To create such a relationship, you need two tables. The first table, referred to as the parent, must have a column that can uniquely identify each record. Such a column is created as, and is called the primary key. The other table, referred to as a child, must have a column that will allow it to be related to the primary key of the parent table. Such a column is referred to as a foreign key because it acts as an "ambassador". Although it is created in the child table, it is only a representative of the records of the parent table.

To create a relationship between two tables, both must have a column that will be used as the link. both columns must have the same data type. Although they don't have to have the same  name, it makes it convenient to use the same name.

It is particularly easy to create a relationship between two tables

Practical Learning: Creating Relationships

  1. In the Database window, right-click the Transactions table and click Design View
  2. Right-click TransactionDate and click Insert Rows
  3. Type CustomerID and press Tab
  4. Set the Data Type to Number
  5. Save and close the table
  6. In the Database window, click the New button
  7. In the first Field Name, type LoanProcessingID and press Enter
  8. On the toolbar, click the Primary Key button
  9. Complete the table as follows
     
    Field Name Data Type
    LoanProcessingID AutoNumber
    ProcessingDate DateTime
    CustomerID Number
    LoanNumber Text
    TypeOfLoanID Number
    LoanAmount Currency
    Notes Memo
  10. Save the table as LoanProcessing and close it

Overview

Tables relationships are prepared in the table but they are managed in the Relationships window. In the Relationships window, you can connect a foreign key of a child table to the primary key of the parent table

Practical Learning: Managing Relationships

  1. On the main menu, click Tools -> Relationships...
  2. On the Show Table dialog box, click each table once and click Add
  3. After selecting all tables, click Close
  4. In the Relationships window, click and drag CustomerID from the Customers list and drop it on top of CustomerID in the LoanProcessing list
  5. On the Edit Relationship dialog box that comes up, click the check box then click the other two check boxes and click Create
 

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