Using PHP/MySQL with error checking

<?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);
?>