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Retrieving Data The process of retrieving data once a connection has been made to the MySQL server is similar to the process of interacting with the data through the mysql client. The first thing that needs to be addressed is the database that holds the table (which in turn holds the data). Selecting a Database In the mysql client, a database is identified (or selected) by the USE <database> command. In PHP, this is accomplished with a PHP MySQL API function called mysql_select_db(). This function identifies the database that should be used for any subsequent requests to the data, which eliminates the need to qualify every table (or other MySQL resource) called with the database name. There are two ways to use this function: • mysql_select_db($db_name, $link_id) – Using the mysql_select_db function in this fashion ensures that the resource that initiated the connection to the MySQL server would be selected with the $link_id. The variable, that is identified here

Operators such as = and != are useful for finding values that are equal to or not equal to a specific exact  comparison value. When it's necessary to find values based on similarity instead, a pattern match is useful.  To perform a pattern match, use value LIKE 'pattern', where value is the value to test and  'pattern' is a pattern string that describes the general form of values to match. Patterns used with the LIKE pattern-matching operator can contain two special characters (called  “metacharacters” or “wildcards”) that stand for something other than themselves: • Percent (%) Character - The percent character matches any sequence of zero or more characters. For example, the pattern 'a%' matches any string that begins with 'a', '%b' matches any string  that ends with 'b', and '%c%' matches any string that contains a 'c'. The pattern '%' matches  any string, including empty strings. • Underscore