blob: cf41f95beb07afd11f57159399f0d6c6a7845c3b (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
|
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
<title>CodeIgniter User Guide</title>
<style type='text/css' media='all'>@import url('../userguide.css');</style>
<link rel='stylesheet' type='text/css' media='all' href='../userguide.css' />
<script type="text/javascript" src="../nav/nav.js"></script>
<script type="text/javascript" src="../nav/prototype.lite.js"></script>
<script type="text/javascript" src="../nav/moo.fx.js"></script>
<script type="text/javascript">
window.onload = function() {
myHeight = new fx.Height('nav', {duration: 400});
myHeight.hide();
}
</script>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta http-equiv='expires' content='-1' />
<meta http-equiv= 'pragma' content='no-cache' />
<meta name='robots' content='all' />
<meta name='author' content='Rick Ellis' />
<meta name='description' content='CodeIgniter User Guide' />
</head>
<body>
<!-- START NAVIGATION -->
<div id="nav"><div id="nav_inner"><script type="text/javascript">create_menu('../');</script></div></div>
<div id="nav2"><a name="top"></a><a href="javascript:void(0);" onclick="myHeight.toggle();"><img src="../images/nav_toggle.jpg" width="153" height="44" border="0" title="Toggle Table of Contents" alt="Toggle Table of Contents" /></a></div>
<div id="masthead">
<table cellpadding="0" cellspacing="0" border="0" style="width:100%">
<tr>
<td><h1>CodeIgniter User Guide Version 1.5.4</h1></td>
<td id="breadcrumb_right"><a href="../toc.html">Table of Contents Page</a></td>
</tr>
</table>
</div>
<!-- END NAVIGATION -->
<!-- START BREADCRUMB -->
<table cellpadding="0" cellspacing="0" border="0" style="width:100%">
<tr>
<td id="breadcrumb">
<a href="http://www.codeigniter.com/">CodeIgniter Home</a> ›
<a href="../index.html">User Guide Home</a> ›
<a href="index.html">Database Library</a> ›
Transactions
</td>
<td id="searchbox"><form method="get" action="http://www.google.com/search"><input type="hidden" name="as_sitesearch" id="as_sitesearch" value="codeigniter.com/user_guide/" />Search User Guide <input type="text" class="input" style="width:200px;" name="q" id="q" size="31" maxlength="255" value="" /> <input type="submit" class="submit" name="sa" value="Go" /></form></td>
</tr>
</table>
<!-- END BREADCRUMB -->
<br clear="all" />
<!-- START CONTENT -->
<div id="content">
<h1>Transactions</h1>
<p>CodeIgniter's database abstraction allows you to use <dfn>transactions</dfn> with databases that support transaction-safe table types. In MySQL, you'll need
to be running InnoDB or BDB table types rather then the more common MyISAM. Most other database platforms support transactions natively.</p>
<p>If you are not familiar with
transactions we recommend you find a good online resource to learn about them for your particular database. The information below assumes you
have a basic understanding of transactions.
</p>
<h2>CodeIgniter's Approach to Transactions</h2>
<p>CodeIgniter utilizes an approach to transactions that is very similar to the process used by the popular database class ADODB. We've chosen that approach
because it greatly simplifies the process of running transactions. In most cases all that is required are two lines of code.</p>
<p>Traditionally, transactions have required a fair amount of work to implement since they demand that you to keep track of your queries
and determine whether to <dfn>commit</dfn> or <dfn>rollback</dfn> based on the success or failure of your queries. This is particularly cumbersome with
nested queries. In contrast,
we've implemented a smart transaction system that does all this for you automatically (you can also manage your transactions manually if you choose to,
but there's really no benefit).</p>
<h2>Running Transactions</h2>
<p>To run your queries using transactions you will use the <dfn>$this->db->trans_start()</dfn> and <dfn>$this->db->trans_complete()</dfn> functions as follows:</p>
<code>
<kbd>$this->db->trans_start();</kbd><br />
$this->db->query('AN SQL QUERY...');<br />
$this->db->query('ANOTHER QUERY...');<br />
$this->db->query('AND YET ANOTHER QUERY...');<br />
<kbd>$this->db->trans_complete();</kbd>
</code>
<p>You can run as many queries as you want between the start/complete functions and they will all be committed or rolled back based on success or failure
of any given query.</p>
<h2>Managing Errors</h2>
<p>If you have error reporting enabled in your <dfn>config/database.php</dfn> file you'll see a standard error message if the commit was unsuccessful. If debugging is turned off, you can
manage your own errors like this:</p>
<code>
$this->db->trans_start();<br />
$this->db->query('AN SQL QUERY...');<br />
$this->db->query('ANOTHER QUERY...');<br />
$this->db->trans_complete();<br />
<br />
if (<kbd>$this->db->trans_status()</kbd> === FALSE)<br />
{<br />
// generate an error... or use the log_message() function to log your error<br />
}
</code>
<h2>Enabling Transactions</h2>
<p>Transactions are enabled automatically the moment you use <dfn>$this->db->trans_start()</dfn>. If you would like to disable transactions you
can do so using <dfn>$this->db->trans_off()</dfn>:</p>
<code>
<kbd>$this->db->trans_off()</kbd><br /><br />
$this->db->trans_start();<br />
$this->db->query('AN SQL QUERY...');<br />
$this->db->trans_complete();
</code>
<p class="important">When transactions are disabled, your queries will be auto-commited, just as they are when running queries without transactions.</p>
<h2>Test Mode</h2>
<p>You can optionally put the transaction system into "test mode", which will cause your queries to be rolled back -- even if the queries produce a valid result.
To use test mode simply set the first parameter in the <dfn>$this->db->trans_start()</dfn> function to <samp>TRUE</samp>:</p>
<code>
$this->db->trans_start(<samp>TRUE</samp>); // Query will be rolled back<br />
$this->db->query('AN SQL QUERY...');<br />
$this->db->trans_complete();
</code>
<h2>Running Transactions Manually</h2>
<p>If you would like to run transactions manually you can do so as follows:</p>
<code>
$this->db->trans_begin();<br /><br />
$this->db->query('AN SQL QUERY...');<br />
$this->db->query('ANOTHER QUERY...');<br />
$this->db->query('AND YET ANOTHER QUERY...');<br />
<br />
if ($this->db->trans_status() === FALSE)<br />
{<br />
$this->db->trans_rollback();<br />
}<br />
else<br />
{<br />
$this->db->trans_commit();<br />
}<br />
</code>
<p class="important"><strong>Note:</strong> Make sure to use <kbd>$this->db->trans_begin()</kbd> when running manual transactions, <strong>NOT</strong>
<dfn>$this->db->trans_start()</dfn>.</p>
</div>
<!-- END CONTENT -->
<div id="footer">
<p>
Previous Topic: <a href="fields.html">Field MetaData</a> ·
<a href="#top">Top of Page</a> ·
<a href="../index.html">User Guide Home</a> ·
Next Topic: <a href="table_data.html">Table Metadata</a>
</p>
<p><a href="http://www.codeigniter.com">CodeIgniter</a> · Copyright © 2007 · <a href="http://ellislab.com/">Ellislab, Inc.</a></p>
</div>
</body>
</html>
|
