Resumo de Elements Of A Database

Elements of a Database

The important database objects are Tables, Queries, Forms, Reports, Macros and Modules.

(i) Tables: A Table is a collection of data about a specific topic, such as products, students, and suppliers. Using a separate table for each topic means that you use that data only once, which makes your database more efficient and reduces data-entry errors. Tables organize data into columns and rows . MS-Access has a table datasheet view, wherein you can add, edit or view the data in a table. You can also check the spelling and print your table?s data, filter or sort records, change the datasheet?s appearance, or change the table?s structure by adding or deleting columns. In the MS-Access table Design view, you a create an entire table from scratch, or add, delete or customize an existing table?s fields.

(ii) Queries: You use queries to ask questions about your data. Queries are also used to view, change and analyze this data in different ways. Queries can be used as the source of records for Forms and reports. The most common type of query is a select query. A select query retrieves data from one or more tables, using criteria you specify, and then displays it in the order you want. You can create a query with a wizard or from scratch in query design view. In design view, you specify the data you want to work with by adding the tables or queries that contain the data, and then by filling the design grid.

You can formulate simple queries that look for records in a single table, or design complex queries that involve multiple tables and criteria.

(iii)Forms: When a table is opened, it gets opened in gets presented in a datasheet view. In datasheet view, data is presented in rows and columns. In most cases it is better to use the Form to enter or modify data. Developing a database form from scratch is a tedious task. MS-Access has a form wizard with which a form can be created after asking a number of questions about what you want to see. Columnar auto form creates a form with one record per page and fields arranged in columns.

(iv)Reports: Reports are another type of objects used in MS-Access to view and print data from a single table as well as more than one table.

Differences between Forms and Reports: Reports are similar to forms and in fact the report design window shares many of the features of the form design window. There are however some important differences between theses two types of objects. One difference is that forms are primarily used to edit or view data on your computer screen. When you move through a form you usually navigate from one record to another; Reports on the other hand can be previewed on the screen as well but their main purpose is to provide information on a neatly printed page. Another difference between forms and reports is that reports have special features that help you to summarize data. It is not possible to view this kind of summary information using a form

(v)Macros: A macro executes one or more database commands automatically when it is executed. Macros are meant for automating those tasks that you do over and over again i.e.

· Printing month-end reports.
· Adding new record to a table.
· Printing letters to customers periodically.

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