summaryrefslogtreecommitdiffstats
path: root/www/session/sqlite3changeset_invert.html
blob: d97c44fb8c7e0c44e2831e3a2b818045b48c7a30 (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
<!DOCTYPE html>
<html><head>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<link href="../sqlite.css" rel="stylesheet">
<title>Invert A Changeset</title>
<!-- path=../ -->
</head>
<body>
<div class=nosearch>
<a href="../index.html">
<img class="logo" src="../images/sqlite370_banner.gif" alt="SQLite" border="0">
</a>
<div><!-- IE hack to prevent disappearing logo --></div>
<div class="tagline desktoponly">
Small. Fast. Reliable.<br>Choose any three.
</div>
<div class="menu mainmenu">
<ul>
<li><a href="../index.html">Home</a>
<li class='mobileonly'><a href="javascript:void(0)" onclick='toggle_div("submenu")'>Menu</a>
<li class='wideonly'><a href='../about.html'>About</a>
<li class='desktoponly'><a href="../docs.html">Documentation</a>
<li class='desktoponly'><a href="../download.html">Download</a>
<li class='wideonly'><a href='../copyright.html'>License</a>
<li class='desktoponly'><a href="../support.html">Support</a>
<li class='desktoponly'><a href="../prosupport.html">Purchase</a>
<li class='search' id='search_menubutton'>
<a href="javascript:void(0)" onclick='toggle_search()'>Search</a>
</ul>
</div>
<div class="menu submenu" id="submenu">
<ul>
<li><a href='../about.html'>About</a>
<li><a href='../docs.html'>Documentation</a>
<li><a href='../download.html'>Download</a>
<li><a href='../support.html'>Support</a>
<li><a href='../prosupport.html'>Purchase</a>
</ul>
</div>
<div class="searchmenu" id="searchmenu">
<form method="GET" action="../search">
<select name="s" id="searchtype">
<option value="d">Search Documentation</option>
<option value="c">Search Changelog</option>
</select>
<input type="text" name="q" id="searchbox" value="">
<input type="submit" value="Go">
</form>
</div>
</div>
<script>
function toggle_div(nm) {
var w = document.getElementById(nm);
if( w.style.display=="block" ){
w.style.display = "none";
}else{
w.style.display = "block";
}
}
function toggle_search() {
var w = document.getElementById("searchmenu");
if( w.style.display=="block" ){
w.style.display = "none";
} else {
w.style.display = "block";
setTimeout(function(){
document.getElementById("searchbox").focus()
}, 30);
}
}
function div_off(nm){document.getElementById(nm).style.display="none";}
window.onbeforeunload = function(e){div_off("submenu");}
/* Disable the Search feature if we are not operating from CGI, since */
/* Search is accomplished using CGI and will not work without it. */
if( !location.origin || !location.origin.match || !location.origin.match(/http/) ){
document.getElementById("search_menubutton").style.display = "none";
}
/* Used by the Hide/Show button beside syntax diagrams, to toggle the */
function hideorshow(btn,obj){
var x = document.getElementById(obj);
var b = document.getElementById(btn);
if( x.style.display!='none' ){
x.style.display = 'none';
b.innerHTML='show';
}else{
x.style.display = '';
b.innerHTML='hide';
}
return false;
}
var antiRobot = 0;
function antiRobotGo(){
if( antiRobot!=3 ) return;
antiRobot = 7;
var j = document.getElementById("mtimelink");
if(j && j.hasAttribute("data-href")) j.href=j.getAttribute("data-href");
}
function antiRobotDefense(){
document.body.onmousedown=function(){
antiRobot |= 2;
antiRobotGo();
document.body.onmousedown=null;
}
document.body.onmousemove=function(){
antiRobot |= 2;
antiRobotGo();
document.body.onmousemove=null;
}
setTimeout(function(){
antiRobot |= 1;
antiRobotGo();
}, 100)
antiRobotGo();
}
antiRobotDefense();
</script>
<a href="../session/intro.html"><h2>Session Module C Interface</h2></a><h2>Invert A Changeset</h2><blockquote><pre>int sqlite3changeset_invert(
  int nIn, const void *pIn,       /* Input changeset */
  int *pnOut, void **ppOut        /* OUT: Inverse of input */
);
</pre></blockquote><p>
This function is used to "invert" a changeset object. Applying an inverted
changeset to a database reverses the effects of applying the uninverted
changeset. Specifically:</p>

<p><ul>
  <li> Each DELETE change is changed to an INSERT, and
  <li> Each INSERT change is changed to a DELETE, and
  <li> For each UPDATE change, the old.* and new.* values are exchanged.
</ul></p>

<p>This function does not change the order in which changes appear within
the changeset. It merely reverses the sense of each individual change.</p>

<p>If successful, a pointer to a buffer containing the inverted changeset
is stored in *ppOut, the size of the same buffer is stored in *pnOut, and
SQLITE_OK is returned. If an error occurs, both *pnOut and *ppOut are
zeroed and an SQLite error code returned.</p>

<p>It is the responsibility of the caller to eventually call sqlite3_free()
on the *ppOut pointer to free the buffer allocation following a successful 
call to this function.</p>

<p>WARNING/TODO: This function currently assumes that the input is a valid
changeset. If it is not, the results are undefined.
</p><p>See also lists of
  <a href="../session/objlist.html">Objects</a>,
  <a href="../session/constlist.html">Constants</a>, and
  <a href="../session/funclist.html">Functions</a>.</p>