# Building Simple Databases

## Introduction

To learn the basics of &kexi;, you could build a simple database utilizing most elementary &kexi;'s features. To make things simpler, advanced database design topics will not be covered here.

Start by creating a new empty Phone Book.

Having a new empty database project, perform the following steps:

1. Design database tables. Read .

2. Enter data into tables. Read .

3. Design database queries. Read .

4. Design forms. Read .

5. Use forms to enter data. Read .

## Designing Database Tables

First, there will be two tables added to your database: persons and phone_numbers. These are exactly the same tables as described in chapter Database and spreadsheet. A layout for Persons can be found in section Data integrity and validity in that chapter.

1. Select Insert Table... from the Menubar. You can also use the button Create object: table on the Project Navigator's toolbar.

2. The Table Designer's window will appear. Looking at the top of designer's window you will notice that &kexi; proposed you a generic name like template for the new table. The table design is not saved yet so you will be able to assign more proper name later. Moreover, because of the same reason, the table name is not yet visible in the Project Navigator.

### The Table Designer window

#### Table Designer window consists of following columns:

- PK - Primary Key.

- Field Caption - caption of the field which will be displayed during data entering.

- Data Type - a combo box containing a list of data types, allowing to set a main rule for entered data for a given field. For example, when an integer number data type is set for a field, a database user will not able to enter letter characters into this field.

- Comments - you can enter here any information useful for understanding what the given field is provided for. This additional text will be saved within the table design and only visible in design mode.

In the Table designer window, every row corresponds to a single table field. You can recognize you are in design mode because the Switch to design view button is toggled on within the main &kexi; toolbar.

#### Designing the Persons table

1. In the first row click on the cell in the Field Caption column and enter Name as field caption.

   #### Notes about field names and captions

   - Every table field must have a name and a caption, these cannot be empty.

   - Field name is a word used by the database, usually not visible for users of the database application. The name may not contain special (national) characters (like ±, ¶, Ü) or space characters. The name must only contain roman letters, numbers and underscore sign "_". Use the latter instead of spaces or dashes.

   - Field names must be started with a letter or underscore sign "_", never with a number.

   - It does not matter whether you are using small or capital letters. For &kexi; the database name "Persons" is the same as "persons".

   - Field caption, on the other hand, allows you to enter any letters and special characters. It will be displayed for users of the database application.

2. #### In a similar way, enter the following fields into the table design:

   - surname

   - street

   - house_number

   - city

3. All the above fields, except house_number, are of type text. Change house_number field's type to integer number. To do this, click on a cell in the Data Type column, house_number row and then click on drop down list's button (you can also press F4 or &Alt;Down. The list of data types will appear. Select the Integer number type.

   From now on, the house_number field only accepts numbers.

4. Persons table design is ready. Click Switch to data view button on the toolbar to finish designing and switch to Data View for the table. This allows you entering data into the table.

5. As the design is not yet saved in the database, the Save Object As dialog window appears. You need to specify the name for the new table.

   &kexi; offers a generic name like Table1. To change the name, enter Persons into the Caption field and press the Enter key or click the OK button. The Caption field will be used to display the table to database end-users, &eg; as a form. Unlike the name, the caption can contain any characters including spaces and special characters.

   Note that filling the Caption field automatically fills the Name field. For your convenience the rule for using only letters, numbers and the "_" character is kept. You can alter the contents of the Name field if you want to.

6. You are asked about an agreement for automatic adding of primary key to the table. Click Add primary key button to continue.

7. The Persons table has been created and opened in Data View. Its name appears in the Project Navigator pane.

8. Create the phone_numbers table, in a similar way as persons table.

9. Create a person field of type Integer number and phone of type Text. Do not use a number type here because phone numbers can have many different forms and prefixes.

10. Click Switch to data view button on the toolbar and enter Phones caption for the table. As for your previous table, allow &kexi; to automatically create a primary key.

&enteringdataintotables;

&querydesigning;

&designingforms;

&enteringdatausingforms;