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Below is a documented code example showing how to use the MySQL functions to connect and query your database (and check for errors). Please note that using the MySQL extension is NOT RECOMMENDED. This extension is no longer maintained and will be deprecated soon. If you want your scripts to be future proof it is better to switch to MySQLi or PDO.

If there are any questions, or you want to see different features, let me know.

Edited by pritaeas: Addition

Votes + Comments
This is beautiful :D
Is this gonna be a sticky not a Code Snippet!
<?php
    // define a variable to switch on/off error messages
    $mysqlDebug = true;
    
    // connect to your database
    $dbLink = mysql_connect('localhost', 'myuser', 'mypassword');
    
    // mysql_connect will return false if the connect failed
    if (!$dbLink) {
        echo '<p>There was an error connecting to the database!</p>';
        if ($mysqlDebug) {
            // mysql_error returns the latest error message,
            // hopefully clarifying the problem
            echo mysql_error();
        }
        
        // since there is no database connection your queries will fail,
        // quit processing
        die();
    }
    
    // if you use a single database, selecting it will simplify your queries
    // mysql_select_db will return false if the database could not be selected
    if (!mysql_select_db('mydatabase')) {
        echo '<p>There was an error selecting the database!</p>';
        if ($mysqlDebug) {
            echo mysql_error();
        }
        
        // since there is no database selected your queries will fail,
        // close the connection and quit processing
        mysql_close($dbLink);
        die();
    }
    
    // create a query that should return a single record
    // the backticks around the table and column names are optional
    // they are required only when a name matches a reserved word (e.g. `date`)
    $query = 'SELECT * FROM `mytable` ORDER BY `mycolumn` LIMIT 1';
    
    // execute the query
    // passing the connection link as a parameter is optional
    // but useful if you are accessing more than one database
    // mysql_query returns false on error, and a resource on success
    $result = mysql_query($query, $dbLink);
    if (!$result and $mysqlDebug) {
        // the query failed and debugging is enabled
        echo "<p>There was an error in query: $query</p>";
        echo mysql_error();
    }
    if ($result) {
        // the query was successful
        // get the result (if any)
        // mysql_fetch_array returns false if there is no record
        if ($record = mysql_fetch_array($result)) {
            // we have a record so now we can use it
            // output the column by index
            echo $record[0];
            // output the column by name
            echo $record['mycolumn'];
        }
		else {
			echo '<p>No record found.</p>';
		}
        
        // when you are done with the result, free it
        // it is optional, but preferred
        mysql_free_result($result);
    }
    
    // now get multiple records
    $query = 'SELECT * FROM `mytable` ORDER BY `mycolumn` LIMIT 10';
    
    $result = mysql_query($query, $dbLink);
    if (!$result and $mysqlDebug) {
        echo "<p>There was an error in query: $query</p>";
        echo mysql_error();
    }
    if ($result) {
        // perhaps you want to check if there are any rows available
        $recordCount = mysql_num_rows($result);
        if ($recordCount == 0) {
            echo '<p>No records found.</p>';
        }
        else {
	        while ($record = mysql_fetch_array($result)) {
	            echo $record[0];
	            echo $record['mycolumn'];
	        }
        }
        mysql_free_result($result);
    }
    
    // close the database connection (preferred)
    // closing is optional, but not closing the link 
    // will keep the connection lingering until it times out
    mysql_close($dbLink);
?>
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