Database Techniques and PHP

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Picking up where we left off last week in our discussion of databases and PHP, we'll talk about connecting, issuing a query, and more. This article is excerpted from chapter eight of the book Programming PHP, Second Edition, written by Kevin Tatroe, Rasmus Lerdorf, and Peter MacIntyre (O'Reilly, 2006; ISBN: 0596006810). Copyright © 2006 O'Reilly Media, Inc. All rights reserved. Used with permission from the publisher. Available from booksellers or direct from O'Reilly Media.

 Connecting 

Once you have a DSN, create a connection to the database using the connect() method. This returns a database object you’ll use for tasks such as issuing queries and quoting parameters:

  $db = DB::connect(DSN [, options ]);

Theoptions  value can either be Boolean, indicating whether or not the connection is to be persistent, or an array of options settings. Theoptions  values are given in Table 8-2.

Table 8-2. Connection options

Option	Controls
persistent	Connection persists between accesses
optimize	What to optimize for
debug	Display debugging information

By default, the connection is not persistent and no debugging information is displayed. Permitted values foroptimizeare'performance'and'portability'. The default is'performance'. Here’s how to enable debugging and optimize for portability:

  $db = DB::connect($dsn, array('debug' => 1, 'optimize' => 'portability'));

Error Checking

PEAR DB methods return DB_ERROR if an error occurs. You can check for this with DB::isError():

  $db = DB::connect($datasource);
  if (DB::isError($db)) {
    die($db->getMessage());
  }

TheDB::isError()method returnstrueif an error occurred while working with the database object. If there was an error, the usual behavior is to stop the program and display the error message reported by thegetMessage()method. You can callgetMessage()on any PEAR DB object.

Next: Issuing a Query >>
 

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This article is excerpted from chapter eight of the book Programming PHP, Second Edition, written by Kevin Tatroe, Rasmus Lerdorf, and Peter MacIntyre (O'Reilly, 2006; ISBN: 0596006810). Check it out today at your favorite bookstore. Buy this book now.