PHP —

Data entry and saving records to a database

Tutorial 6 introduces techniques to write data to a database. We illustrate the principles of writing data by developing a simple customer membership <form> in Tutorial 6, Tutorial 7, and Tutorial 8. The complete implementation of the customer membership process is discussed in Tutorial 10, and the completed <form> is shown in Figure 1-7.

Figure 1-7. The customer <form> collects and updates member information
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Writing data requires careful consideration of how other users are interacting with the database at the same time. We introduce the theory and practice of writing to databases in Tutorial 6, as well as the PHP functions to manage and report on the writing process.

Validation in the client and middle tiers

We continue our development of the simplified customer <form> in Chapter 7, where we introduce validation in the client and middle tiers. Validation in both tiers is important. Client-side validation with JavaScript lightens the web-server load in the middle tier, is fast for the user, and has no network overhead. Server-side validation is also important: users can bypass client-tier validation or may not have it configured correctly, it may not be supported by the browser, and complete and complex validation might be possible only in the middle tier.

Figure 1-8 shows a customer <form> validation error message produced using the client-side JavaScript techniques discussed in Chapter 7.

Figure 1-8. A JavaScript validation error for the winestore customer <form>
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