How SQL works....

perfectturmoil · May 24, 2006

Hey. This post kinda belongs in several different forums, but I figured I'd post it here cause its kind of a general question:

When you make a database in SQL, how does it save? Is there a "database file" somewhere? (.mdb or something)?

I'm looking into it for the program that I'm writing for work. I need to write entries to the database, and then read data out of it. So far, I've just used MS Access for the databasing part, but I need to upgrade to SQL if this program is going to be implemented. I've read a bunch of tutorials.. and stuff.. They say things like this:

Code:

Session("DB_ConnectionString") = _
 "DSN=myDSN;UID=myUID;PWD=myPWD;DB=myDB;HOST=myHOST;SERV=MyService;SRVR=MyServer;PRO=MyProtocol;"
 Dim objConnect   'Declare the connection variable
 'Set up Connection Object
 Set objConnect = Server.CreateObject("ADODB.Connection")
 objConnect.Open Session("DB_ConnectionString")

Theres a bunch of different ways (and I'm using both VB and ASP..) but they all sorta do something similar to that.. with the DSN and user id and all that good stuff (or replace DSN with more info about the server.. whatever)

BUT.. they also usually say "Oh yeah, if you just have the file on the server, you can direct link it".. The Webserver for this program will also be holding the database. Does that mean that the there is an "SQL file" on the computer that I can direct link to the same way as I did the Access file? Also, for the VB entry part of the code, all of the computers are networked so the same thing should apply if it works that way.

The person who's gonna set an account on the server up for me is out today. And for some reason MySQL won't install on my computer.. So I can't test it for myself.

Can anyone tell me if my job just got WAY easier? :- ]

Gnufsh · May 24, 2006

Um... you need to send SQL queries to the database engine (which should be runnin gin the background). If you want a web page to connect to the database, I reccomend php.

Ebola · May 24, 2006

Yes SQL hold its data in two files. A log file and a Database file. You used to be able to link to the mdf file in MSDE but for SQL Server you have to use either an odbc, oledb, or sql connection string.

perfectturmoil · May 24, 2006

Gnufsh said:
Um... you need to send SQL queries to the database engine (which should be runnin gin the background). If you want a web page to connect to the database, I reccomend php.

I know all that :- ] I've already built the whole system.. Just using SQL calls to an Access database instead of an SQL database.

BUT - several of the examples give an aside that say "aside from doing it the 'real' way, to open the connection you can just go directly to the file.. CN.open (c:/whatever.mdb) or something like that. Is this a misunderstanding? Or might I be able to open the SQL connection the exact same way as I open the access database?

Thats my question :- ]

perfectturmoil · May 24, 2006

Ebola said:
Yes SQL hold its data in two files. A log file and a Database file. You used to be able to link to the mdf file in MSDE but for SQL Server you have to use either an odbc, oledb, or sql connection string.

would ODBC be something like this?

CN = New ADODB.Connection
CN.Provider = "MICROSOFT.JET.OLEDB.4.0"

I am 'Captain get things done and beat the deadline by learning and finding what is neccesary'. I built an entire image capture and web searcheable database system in 2 weeks without knowing how to use Visual Basic, Visual Studio, ASP, OR Access at all. With tutorials, free code snips, and all sorts of looking stuff up, I got it working - but doing it that way I don't really know the terminology or the ins and outs of the environment and stuff like that.. Sort of a hamper in some respects, but it sure does get a lot of work done :- ]

perfectturmoil · May 24, 2006

Ok.. you also mentioned OLEDB. And it says that right in my cut-and-paste. Thats kinda dumb.. I figure thats what I'm using, correct? :- ]

BTW: To anybody who's bad talk me about 'Not knowing what I'm doing'.. I'm not a programmer, I'm EE, not CE or CS.. This stuff ISN'T my thing, I just took on the project instead of just suggesting the company go out and spend $15k-30k on something thats the same as what I figured I could accomplish. So there :- p

Malpine Walis · May 24, 2006

Well Access can handle either SQL or ODBC with no more problems than anything by MS can handle fairly standards stuff. Even teh really ancient version that I have here at work.

-maddog- · May 24, 2006

PHP:

<?php
/***************************************************************************
 *                                posting.php
 *                            -------------------
 *   begin                : Saturday, Feb 13, 2001
 *   copyright            : (C) 2001 The phpBB Group
 *   email                : [email protected]
 *
 *   $Id: posting.php,v 1.159.2.27 2005/10/30 15:17:13 acydburn Exp $
 *
 *
 ***************************************************************************/

/***************************************************************************
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 ***************************************************************************/

define('IN_PHPBB', true);
$phpbb_root_path = './';
include($phpbb_root_path . 'extension.inc');
include($phpbb_root_path . 'common.'.$phpEx);
include($phpbb_root_path . 'includes/bbcode.'.$phpEx);
include($phpbb_root_path . 'includes/functions_post.'.$phpEx);

//
// Check and set various parameters
//
$params = array('submit' => 'post', 'preview' => 'preview', 'delete' => 'delete', 'poll_delete' => 'poll_delete', 'poll_add' => 'add_poll_option', 'poll_edit' => 'edit_poll_option', 'mode' => 'mode');
while( list($var, $param) = @each($params) )
{
	if ( !empty($HTTP_POST_VARS[$param]) || !empty($HTTP_GET_VARS[$param]) )
	{
		$$var = ( !empty($HTTP_POST_VARS[$param]) ) ? htmlspecialchars($HTTP_POST_VARS[$param]) : htmlspecialchars($HTTP_GET_VARS[$param]);
	}
	else
	{
		$$var = '';
	}
}

$confirm = isset($HTTP_POST_VARS['confirm']) ? true : false;

$params = array('forum_id' => POST_FORUM_URL, 'topic_id' => POST_TOPIC_URL, 'post_id' => POST_POST_URL);
while( list($var, $param) = @each($params) )
{
	if ( !empty($HTTP_POST_VARS[$param]) || !empty($HTTP_GET_VARS[$param]) )
	{
		$$var = ( !empty($HTTP_POST_VARS[$param]) ) ? intval($HTTP_POST_VARS[$param]) : intval($HTTP_GET_VARS[$param]);
	}
	else
	{
		$$var = '';
	}
}

$refresh = $preview || $poll_add || $poll_edit || $poll_delete;
$orig_word = $replacement_word = array();

//
// Set topic type
//
$topic_type = ( !empty($HTTP_POST_VARS['topictype']) ) ? intval($HTTP_POST_VARS['topictype']) : POST_NORMAL;
$topic_type = ( in_array($topic_type, array(POST_NORMAL, POST_STICKY, POST_ANNOUNCE)) ) ? $topic_type : POST_NORMAL;

//
// If the mode is set to topic review then output
// that review ...
//
if ( $mode == 'topicreview' )
{
	require($phpbb_root_path . 'includes/topic_review.'.$phpEx);

	topic_review($topic_id, false);
	exit;
}
else if ( $mode == 'smilies' )
{
	generate_smilies('window', PAGE_POSTING);
	exit;
}

//
// Start session management
//
$userdata = session_pagestart($user_ip, PAGE_POSTING);
init_userprefs($userdata);
//
// End session management
//

//
// Was cancel pressed? If so then redirect to the appropriate
// page, no point in continuing with any further checks
//
if ( isset($HTTP_POST_VARS['cancel']) )
{
	if ( $post_id )
	{
		$redirect = "viewtopic.$phpEx?" . POST_POST_URL . "=$post_id";
		$post_append = "#$post_id";
	}
	else if ( $topic_id )
	{
		$redirect = "viewtopic.$phpEx?" . POST_TOPIC_URL . "=$topic_id";
		$post_append = '';
	}
	else if ( $forum_id )
	{
		$redirect = "viewforum.$phpEx?" . POST_FORUM_URL . "=$forum_id";
		$post_append = '';
	}
	else
	{
		$redirect = "index.$phpEx";
		$post_append = '';
	}

	redirect(append_sid($redirect, true) . $post_append);
}

//
// What auth type do we need to check?
//
$is_auth = array();
switch( $mode )
{
	case 'newtopic':
		if ( $topic_type == POST_ANNOUNCE )
		{
			$is_auth_type = 'auth_announce';
		}
		else if ( $topic_type == POST_STICKY )
		{
			$is_auth_type = 'auth_sticky';
		}
		else
		{
			$is_auth_type = 'auth_post';
		}
		break;
	case 'reply':
	case 'quote':
		$is_auth_type = 'auth_reply';
		break;
	case 'editpost':
		$is_auth_type = 'auth_edit';
		break;
	case 'delete':
	case 'poll_delete':
		$is_auth_type = 'auth_delete';
		break;
	case 'vote':
		$is_auth_type = 'auth_vote';
		break;
	case 'topicreview':
		$is_auth_type = 'auth_read';
		break;
	default:
		message_die(GENERAL_MESSAGE, $lang['No_post_mode']);
		break;
}

//
// Here we do various lookups to find topic_id, forum_id, post_id etc.
// Doing it here prevents spoofing (eg. faking forum_id, topic_id or post_id
//
$error_msg = '';
$post_data = array();
switch ( $mode )
{
	case 'newtopic':
		if ( empty($forum_id) )
		{
			message_die(GENERAL_MESSAGE, $lang['Forum_not_exist']);
		}

		$sql = "SELECT * 
			FROM " . FORUMS_TABLE . " 
			WHERE forum_id = $forum_id";
		break;

	case 'reply':
	case 'vote':
		if ( empty( $topic_id) )
		{
			message_die(GENERAL_MESSAGE, $lang['No_topic_id']);
		}

		$sql = "SELECT f.*, t.topic_status, t.topic_title, t.topic_type  
			FROM " . FORUMS_TABLE . " f, " . TOPICS_TABLE . " t
			WHERE t.topic_id = $topic_id
				AND f.forum_id = t.forum_id";
		break;

	case 'quote':
	case 'editpost':
	case 'delete':
	case 'poll_delete':
		if ( empty($post_id) )
		{
			message_die(GENERAL_MESSAGE, $lang['No_post_id']);
		}

		$select_sql = (!$submit) ? ', t.topic_title, p.enable_bbcode, p.enable_html, p.enable_smilies, p.enable_sig, p.post_username, pt.post_subject, pt.post_text, pt.bbcode_uid, u.username, u.user_id, u.user_sig, u.user_sig_bbcode_uid' : '';
		$from_sql = ( !$submit ) ? ", " . POSTS_TEXT_TABLE . " pt, " . USERS_TABLE . " u" : '';
		$where_sql = ( !$submit ) ? "AND pt.post_id = p.post_id AND u.user_id = p.poster_id" : '';

		$sql = "SELECT f.*, t.topic_id, t.topic_status, t.topic_type, t.topic_first_post_id, t.topic_last_post_id, t.topic_vote, p.post_id, p.poster_id" . $select_sql . " 
			FROM " . POSTS_TABLE . " p, " . TOPICS_TABLE . " t, " . FORUMS_TABLE . " f" . $from_sql . " 
			WHERE p.post_id = $post_id 
				AND t.topic_id = p.topic_id 
				AND f.forum_id = p.forum_id
				$where_sql";
		break;

	default:
		message_die(GENERAL_MESSAGE, $lang['No_valid_mode']);
}

if ( $result = $db->sql_query($sql) )
{
	$post_info = $db->sql_fetchrow($result);
	$db->sql_freeresult($result);

	$forum_id = $post_info['forum_id'];
	$forum_name = $post_info['forum_name'];

	$is_auth = auth(AUTH_ALL, $forum_id, $userdata, $post_info);

	if ( $post_info['forum_status'] == FORUM_LOCKED && !$is_auth['auth_mod']) 
	{ 
	   message_die(GENERAL_MESSAGE, $lang['Forum_locked']); 
	} 
	else if ( $mode != 'newtopic' && $post_info['topic_status'] == TOPIC_LOCKED && !$is_auth['auth_mod']) 
	{ 
	   message_die(GENERAL_MESSAGE, $lang['Topic_locked']); 
	} 

	if ( $mode == 'editpost' || $mode == 'delete' || $mode == 'poll_delete' )
	{
		$topic_id = $post_info['topic_id'];

		$post_data['poster_post'] = ( $post_info['poster_id'] == $userdata['user_id'] ) ? true : false;
		$post_data['first_post'] = ( $post_info['topic_first_post_id'] == $post_id ) ? true : false;
		$post_data['last_post'] = ( $post_info['topic_last_post_id'] == $post_id ) ? true : false;
		$post_data['last_topic'] = ( $post_info['forum_last_post_id'] == $post_id ) ? true : false;
		$post_data['has_poll'] = ( $post_info['topic_vote'] ) ? true : false; 
		$post_data['topic_type'] = $post_info['topic_type'];
		$post_data['poster_id'] = $post_info['poster_id'];

		if ( $post_data['first_post'] && $post_data['has_poll'] )
		{
			$sql = "SELECT * 
				FROM " . VOTE_DESC_TABLE . " vd, " . VOTE_RESULTS_TABLE . " vr 
				WHERE vd.topic_id = $topic_id 
					AND vr.vote_id = vd.vote_id 
				ORDER BY vr.vote_option_id";
			if ( !($result = $db->sql_query($sql)) )
			{
				message_die(GENERAL_ERROR, 'Could not obtain vote data for this topic', '', __LINE__, __FILE__, $sql);
			}

			$poll_options = array();
			$poll_results_sum = 0;
			if ( $row = $db->sql_fetchrow($result) )
			{
				$poll_title = $row['vote_text'];
				$poll_id = $row['vote_id'];
				$poll_length = $row['vote_length'] / 86400;

				do
				{
					$poll_options[$row['vote_option_id']] = $row['vote_option_text']; 
					$poll_results_sum += $row['vote_result'];
				}
				while ( $row = $db->sql_fetchrow($result) );
			}
			$db->sql_freeresult($result);

			$post_data['edit_poll'] = ( ( !$poll_results_sum || $is_auth['auth_mod'] ) && $post_data['first_post'] ) ? true : 0;
		}
		else 
		{
			$post_data['edit_poll'] = ($post_data['first_post'] && $is_auth['auth_pollcreate']) ? true : false;
		}
		
		//
		// Can this user edit/delete the post/poll?
		//
		if ( $post_info['poster_id'] != $userdata['user_id'] && !$is_auth['auth_mod'] )
		{
			$message = ( $delete || $mode == 'delete' ) ? $lang['Delete_own_posts'] : $lang['Edit_own_posts'];
			$message .= '<br /><br />' . sprintf($lang['Click_return_topic'], '<a href="' . append_sid("viewtopic.$phpEx?" . POST_TOPIC_URL . "=$topic_id") . '">', '</a>');

			message_die(GENERAL_MESSAGE, $message);
		}
		else if ( !$post_data['last_post'] && !$is_auth['auth_mod'] && ( $mode == 'delete' || $delete ) )
		{
			message_die(GENERAL_MESSAGE, $lang['Cannot_delete_replied']);
		}
		else if ( !$post_data['edit_poll'] && !$is_auth['auth_mod'] && ( $mode == 'poll_delete' || $poll_delete ) )
		{
			message_die(GENERAL_MESSAGE, $lang['Cannot_delete_poll']);
		}
	}
	else
	{
		if ( $mode == 'quote' )
		{
			$topic_id = $post_info['topic_id'];
		}
		if ( $mode == 'newtopic' )
		{
			$post_data['topic_type'] = POST_NORMAL;
		}

		$post_data['first_post'] = ( $mode == 'newtopic' ) ? true : 0;
		$post_data['last_post'] = false;
		$post_data['has_poll'] = false;
		$post_data['edit_poll'] = false;
	}
	if ( $mode == 'poll_delete' && !isset($poll_id) )
	{
		message_die(GENERAL_MESSAGE, $lang['No_such_post']);
	}
}
else
{
	message_die(GENERAL_MESSAGE, $lang['No_such_post']);
}

//
// The user is not authed, if they're not logged in then redirect
// them, else show them an error message
//
if ( !$is_auth[$is_auth_type] )
{
	if ( $userdata['session_logged_in'] )
	{
		message_die(GENERAL_MESSAGE, sprintf($lang['Sorry_' . $is_auth_type], $is_auth[$is_auth_type . "_type"]));
	}

	switch( $mode )
	{
		case 'newtopic':
			$redirect = "mode=newtopic&" . POST_FORUM_URL . "=" . $forum_id;
			break;
		case 'reply':
		case 'topicreview':
			$redirect = "mode=reply&" . POST_TOPIC_URL . "=" . $topic_id;
			break;
		case 'quote':
		case 'editpost':
			$redirect = "mode=quote&" . POST_POST_URL ."=" . $post_id;
			break;
	}

	redirect(append_sid("login.$phpEx?redirect=posting.$phpEx&" . $redirect, true));
}

//
// Set toggles for various options
//
if ( !$board_config['allow_html'] )
{
	$html_on = 0;
}
else
{
	$html_on = ( $submit || $refresh ) ? ( ( !empty($HTTP_POST_VARS['disable_html']) ) ? 0 : TRUE ) : ( ( $userdata['user_id'] == ANONYMOUS ) ? $board_config['allow_html'] : $userdata['user_allowhtml'] );
}

if ( !$board_config['allow_bbcode'] )
{
	$bbcode_on = 0;
}
else
{
	$bbcode_on = ( $submit || $refresh ) ? ( ( !empty($HTTP_POST_VARS['disable_bbcode']) ) ? 0 : TRUE ) : ( ( $userdata['user_id'] == ANONYMOUS ) ? $board_config['allow_bbcode'] : $userdata['user_allowbbcode'] );
}

if ( !$board_config['allow_smilies'] )
{
	$smilies_on = 0;
}
else
{
	$smilies_on = ( $submit || $refresh ) ? ( ( !empty($HTTP_POST_VARS['disable_smilies']) ) ? 0 : TRUE ) : ( ( $userdata['user_id'] == ANONYMOUS ) ? $board_config['allow_smilies'] : $userdata['user_allowsmile'] );
}

if ( ($submit || $refresh) && $is_auth['auth_read'])

There's a peice of a php file I had lying around. Should be enough you can get somewhat of an idea of what it should look like for SQL.

Gnufsh · May 25, 2006

Doesn't accessing the files directly defeat the point of haveing a database engine?

Elif Tymes · May 25, 2006

Accessing the files directly would be completely useless. It would be slower, and require you to "decode" the way the files are actually stored. Add to that the fact that most SQL servers will lock down the files while the server runs, and you will have quite a fun time on your hands.

How SQL works....

perfectturmoil

Member

Gnufsh

Senior Member

Ebola

Senior Toilet Scrubber

perfectturmoil

Member

perfectturmoil

Member

perfectturmoil

Member

Malpine Walis

Disabled

-maddog-

Member

Gnufsh

Senior Member

Elif Tymes

Member

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