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Once the session has been initialized, the data that must remain persistently can be stored in the superglobal $_SESSION array. The following are examples of storing persistence data to this superglobal array: <?php $_SESSION['fname'] = 'George'; $_SESSION['lname'] = 'Burnes'; ?>

The most complete way to retrieve metadata is by using a SELECT statement against the INFORMATION_SCHEMA database in the MySQL server. However, there are times that is overkill for the data needing to be collected for a PHP application. With that said, PHP offers multiple functions that provide methods for retrieving a small amount of metadata about the data in the MySQL server. Database Metadata The mysql_list_dbs() function retrieves the name of all the databases found on the server that are accessible by the user requesting the information: <?php // Load variables used in mysql_connect and connect to server include "connect_info.php"; $linkID1 = mysql_connect($dbhost,$dbuser,$dbpass) or die("Could not connect to MySQL server"); // Retrieve the names of the databases accessible by the user $schema_results = mysql_list_dbs($linkID1); print "The databases available to the root user are:<br>\n"; while (list($schema) = mysql_fetch

The INFORMATION_SCHEMA is a virtual database that is automatically created and populated by MySQL, there is no need to create an INFORMATION_SCHEMA database. There also is no associated file structure due to the fact that the contents of the data are actual views, rather than logical data being stored in any one location. Only SELECT statements are allowed against the tables in the INFORMATION_SCHEMA database. The following SELECT example demonstrates some of the metadata that can be viewed: <?php // Load variables used in mysql_connect and connect to server include "connect_info.php"; $linkID1 = mysql_connect($dbhost,$dbuser,$dbpass) or die("Could not connect to MySQL server"); // Execute Query to Collect Metadata $query = "SELECT TABLE_NAME, ENGINE, TABLE_ROWS, UPDATE_TIME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA='world'"; $results = mysql_query($query, $linkID1); // Build HTML Table of Results print "<table

String comparisons are somewhat more complex than numeric or temporal comparisons. A letter in  uppercase may compare as the same or different than the same letter in lowercase, and a letter with one  type of accent may be considered the same or different than that letter with another type of accent. • Character Sets and Collations - String expressions contain characters from a particular character  set, which is associated with one of the collations (sorting orders) available for the character set. Characters may consist of single or multiple bytes. A collation can be case insensitive (lettercase  is not significant) or case sensitive (lettercase is significant). The rules that govern string comparison apply in several ways. They determine the result of comparisons  performed explicitly with operators such as = and <, and comparisons performed implicitly by ORDER BY, GROUP BY, and DISTINCT operations. The default character set and collation for literal strings depend on the val