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
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Transactions and batch processes</title>
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2">
<link rel="start" href="index.html" title="GNOME Data Access manual">
<link rel="up" href="index.html" title="GNOME Data Access manual">
<link rel="prev" href="manage-gdavalue.html" title="Managing values">
<link rel="next" href="managing-errors.html" title="Managing errors">
<meta name="generator" content="GTK-Doc V1.10 (XML mode)">
<link rel="stylesheet" href="style.css" type="text/css">
<link rel="chapter" href="introduction.html" title="Introduction">
<link rel="chapter" href="architecture.html" title="libgda architecture">
<link rel="chapter" href="installation.html" title="Installation">
<link rel="chapter" href="connecting.html" title="Beginning">
<link rel="chapter" href="processing-queries.html" title="Processing queries">
<link rel="chapter" href="ch06.html" title="Transactions and batch processes">
<link rel="chapter" href="managing-errors.html" title="Managing errors">
<link rel="chapter" href="main_example.html" title="Full example">
<link rel="chapter" href="migration.html" title="Some formulae for migration from old version">
<link rel="chapter" href="libgda-api.html" title="Client API Reference">
<link rel="chapter" href="libgda-providers.html" title="GDA Providers">
<link rel="chapter" href="libgda-xql.html" title="XML Queries">
<link rel="chapter" href="libgda-reports.html" title="GDA Report Engine">
<link rel="appendix" href="fdl.html" title="Appendix A. GNU Free Documentation License">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table class="navigation" id="top" width="100%" summary="Navigation header" cellpadding="2" cellspacing="2"><tr valign="middle">
<td><a accesskey="p" href="manage-gdavalue.html"><img src="left.png" width="24" height="24" border="0" alt="Prev"></a></td>
<td> </td>
<td><a accesskey="h" href="index.html"><img src="home.png" width="24" height="24" border="0" alt="Home"></a></td>
<th width="100%" align="center">GNOME Data Access manual</th>
<td><a accesskey="n" href="managing-errors.html"><img src="right.png" width="24" height="24" border="0" alt="Next"></a></td>
</tr></table>
<div class="chapter" lang="en">
<div class="titlepage"><div><div><h2 class="title">
<a name="id447560"></a>Transactions and batch processes</h2></div></div></div>
<div class="toc"><dl><dt><span class="sect1"><a href="ch06.html#transactions">Managing transactions</a></span></dt></dl></div>
<div class="sect1" lang="en">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="transactions"></a>Managing transactions</h2></div></div></div>
<p>
The special functions we need to do this are defined in the
<a class="link" href="libgda-GdaTransaction.html" title="GdaTransaction">GdaTransaction</a>,
<a class="link" href="libgda-GdaConnection.html" title="GdaConnection">GdaConnection</a> and
<a class="link" href="libgda-gda-command.html" title="gda-command">GdaCommand</a>
classes, and they are:
</p>
<div class="itemizedlist"><ul type="disc">
<li><p>
<a class="link" href="libgda-GdaTransaction.html#gda-transaction-new" title="gda_transaction_new ()">gda_transaction_new ()</a></p></li>
<li><p>
<a class="link" href="libgda-GdaConnection.html#gda-connection-begin-transaction" title="gda_connection_begin_transaction ()">gda_connection_begin_transaction ()</a></p></li>
<li><p>
<a class="link" href="libgda-GdaConnection.html#gda-connection-commit-transaction" title="gda_connection_commit_transaction ()">gda_connection_commit_transaction ()</a></p></li>
<li><p>
<a class="link" href="libgda-GdaConnection.html#gda-connection-rollback-transaction" title="gda_connection_rollback_transaction ()">gda_connection_rollback_transaction ()</a></p></li>
<li><p>
<a class="link" href="libgda-gda-command.html#gda-command-set-transaction" title="gda_command_set_transaction ()">gda_command_set_transaction ()</a></p></li>
</ul></div>
<p>
Things you have to do to manage transactions are:
</p>
<div class="orderedlist"><ol type="1">
<li><p>Create transaction</p></li>
<li><p>Change, if needed, the isolation level</p></li>
<li><p>Link transaction to a connection</p></li>
<li>
<p>For each command you want to execute:</p>
<div class="orderedlist"><ol type="a">
<li><p>Create command</p></li>
<li><p>Link transaction to command</p></li>
<li><p>Execute command</p></li>
<li><p>Free command</p></li>
</ol></div>
</li>
<li><p>Commit or rollback transaction</p></li>
<li><p>Free transaction</p></li>
</ol></div>
<p>
Here you can see an example:
</p>
<div class="programlistingco">
<pre class="programlisting">
void process_accounts(GdaConnection *connection)
{
GdaTransaction *transaction_one, *transaction_two;
GdaCommand *command;
transaction_one=gda_transaction_new("accounts1");
gda_transaction_set_isolation_level(transaction_one,
GDA_TRANSACTION_ISOLATION_SERIALIZABLE);
gda_connection_begin_transaction(connection,transaction_one);
command=gda_command_new (
"UPDATE accounts SET balance=balance+50"
"WHERE account_code=456",
GDA_COMMAND_TYPE_SQL,
GDA_COMMAND_OPTION_STOP_ON_ERRORS);
gda_command_set_transaction(command,transaction_one);
gda_connection_execute_non_query(connection,command,NULL);
gda_command_free(command);
command=gda_command_new (
"UPDATE accounts SET balance=balance-50"
"WHERE account_code=12",
GDA_COMMAND_TYPE_SQL,
GDA_COMMAND_OPTION_STOP_ON_ERRORS);
gda_command_set_transaction(command,transaction_one);
gda_connection_execute_non_query(connection,command,NULL);
gda_command_free(command);
gda_connection_commit_transaction(connection,transaction_one);
g_object_unref(transaction_one);
transaction_two=gda_transaction_new("accounts2");
gda_transaction_set_isolation_level(transaction_two,
GDA_TRANSACTION_ISOLATION_SERIALIZABLE);
gda_connection_begin_transaction(connection,transaction_two);
command=gda_command_new (
"UPDATE accounts SET balance=balance+400"
"WHERE account_code=456",
GDA_COMMAND_TYPE_SQL,
GDA_COMMAND_OPTION_STOP_ON_ERRORS);
gda_command_set_transaction(command,transaction_two);
gda_connection_execute_non_query(connection,command,NULL);
gda_command_free(command);
command=gda_command_new (
"UPDATE accounts SET balance=balance-400"
"WHERE account_code=12",
GDA_COMMAND_TYPE_SQL,
GDA_COMMAND_OPTION_STOP_ON_ERRORS);
gda_command_set_transaction(command,transaction_two);
gda_connection_execute_non_query(connection,command,NULL);
gda_command_free(command);
gda_connection_rollback_transaction(connection,transaction_two);
g_object_unref(transaction_one);
execute_sql_command(connection,"SELECT * FROM accounts");
}
</pre>
<div class="calloutlist"><table border="0" summary="Callout list">
<tr>
<td width="5%" valign="top" align="left"><p><img src="images/callouts/1.png" alt="1" border="0"></p></td>
<td valign="top" align="left"><p>
Creates first transaction.
</p></td>
</tr>
<tr>
<td width="5%" valign="top" align="left"><p><img src="images/callouts/2.png" alt="2" border="0"></p></td>
<td valign="top" align="left"><p>
Changes the isolation level.
</p></td>
</tr>
<tr>
<td width="5%" valign="top" align="left"><p><img src="images/callouts/3.png" alt="3" border="0"></p></td>
<td valign="top" align="left"><p>
Links it to connection.
</p></td>
</tr>
<tr>
<td width="5%" valign="top" align="left"><p><img src="images/callouts/4.png" alt="4" border="0"></p></td>
<td valign="top" align="left"><p>
Links command to transaction.
</p></td>
</tr>
<tr>
<td width="5%" valign="top" align="left"><p><img src="images/callouts/5.png" alt="5" border="0"></p></td>
<td valign="top" align="left"><p>
Makes commit on transaction.
</p></td>
</tr>
<tr>
<td width="5%" valign="top" align="left"><p><img src="images/callouts/6.png" alt="6" border="0"></p></td>
<td valign="top" align="left"><p>
Frees transaction.
</p></td>
</tr>
<tr>
<td width="5%" valign="top" align="left"><p><img src="images/callouts/7.png" alt="7" border="0"></p></td>
<td valign="top" align="left"><p>
Makes rollback on second transaction.
</p></td>
</tr>
</table></div>
</div>
</div>
</div>
<div class="footer">
<hr>
Generated by GTK-Doc V1.10</div>
</body>
</html>
|
