11.Access 2007 objects.

Access is an object-oriented database management system (DBMS), which means that the entire database is composed of objects. The major database objects are: tables, queries, forms, reports, macros, modules.

• The tables are the containers for all the data in your database.

A table (entity) represents all that the database knows about one subject or kind of thing.

A column (attribute) represents one feature, characteristic, or fact that is true of the table subject.

A row (instance) represents one individual instance of the table subject.

• A query is a question that you ask of your database. You usually use a query to extract a specified set of records from one or more tables.

• Forms are often more convenient than a tabular datasheet for entering and editing table data, especially if a table includes more data than can fit across the screen and you have to scroll right to see the rest. Forms are especially useful for creating a comfortable visual environment for data management.

12.Designing the database. Field and objects names.

The database design process can be broken down into seven steps, each with specific goals and products:

• Determine what the users want from the database and what data is needed to provide the output.

• Decide what tables to include in the database.

• Identify the fields for each table.

• Assign unique fields or combination of fields for each table that ensures no two records are the same.

• Determine how the tables are related to one another.

• Review design and step through procedures with users.

• Create tables and enter data.

• Video 4.22

Choosing Field and table (generally, objects names) names remember the following:

• A name of an object must be unique in the database.

• Field names can have up to 64 characters including letters, numbers, and spaces. Using a mixture of uppercase and lowercase letters can help you explain the field, but Access does not differentiate between cases in field names.

• An object cannot have the same name as a built-in function, property or other reserved name in the Access vocabulary.

  • A name cannot have a leading space or any control characters (ASCII codes 00 – 31).

  • Field names may contain any characters including letters, numbers, spaces, special characters except for a period (.), exclamation mark (!), accent grave (`), square brackets ([]).

  • Remember that though Access accepts spaces in field names, other applications may not. For example, if you plan to program with Visual Basic, do not include spaces in object names. Instead replace them with underscore (_) characters or use a mixture of uppercase and lowercase letters.

13.The concept of data types. Data types in Access 2007. Specifying field data types

There are 11 data types that can be used in Access:TEXT,MEMO,NUMBER,DATE / TIME,CURRENCY,AutoNumber, YES / NO (BOOLEAN),OLE object,HYPERLINK,ATTACHMENT,LookUp Wizard.

• Text. The Text data type is the most common data type and can contain any combination of up to 255 characters and / or numbers.

• Memo. The Memo type is used to store long, but variable-length text possibly relating to the other field data.

• Number. The Number type is used when you want to sort values or use them in calculations, such as adding up the labor hours for a plumbing job or the hours worked by a certain employee during the winter season.

• Date / Time. The Date / Time data type is most useful when you want to sort records chronologically by the value in the field. You can also use it to determine elapsed time. This data type provides a variety of ways to display the data as well.

• Currency. The type is used when you want to store monetary values, such as the cost and bid price of contracted jobs

• AutoNumber. When you specify AutoNumber field, Access guarantees that each record in the table has a unique value in the field, thereby creating a field you can use it as a primary key.

• Access generates a unique value for the field as you enter each new record.

• Yes / No (Boolean). The Yes /No field is useful when you want the equivalent of a check mark in your records.

• OLE Object. When you want to embed or link an object from another source in your

• Hyperlink. When you want your field to jump to another location, or to connect to the

• Attachment. An Attachment field is used to store pictures, images, files from other

• Lookup Wizard. Creates a field limited to a list of valid values. When you select this data type, a wizard helps you create the list and attaches it to your table.

Specifying Field Data Types Several factors come into play as you decide what data types to use:

• The kind of values you plan to allow in the field and how you plan to use them.

• The availability of storage space. With some data types, the field size can be reduced for efficiency.

• The types of operations you can execute with the data. You can count the number of records containing a specific value of most data types in a field, but you can perform mathematical operations on values only in the Number and Currency fields.

• The way you want to sort records. You can sort any field data type except OLE Object and Attachment.

• The way you want to group records for a report or query. You can group on any field data type except Memo, Hyperlink, OLE Object and Attachment.