129 lines
4.8 KiB
HTML
129 lines
4.8 KiB
HTML
<!DOCTYPE html>
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<html><head>
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<meta name="viewport" content="width=device-width, initial-scale=1.0">
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<meta http-equiv="content-type" content="text/html; charset=UTF-8">
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<link href="../sqlite.css" rel="stylesheet">
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<title>Read Data From A BLOB Incrementally</title>
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<!-- path=../ -->
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</head>
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<body>
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<div class=nosearch>
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<a href="../index.html">
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<img class="logo" src="../images/sqlite370_banner.gif" alt="SQLite" border="0">
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</a>
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<div><!-- IE hack to prevent disappearing logo --></div>
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<div class="tagline desktoponly">
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Small. Fast. Reliable.<br>Choose any three.
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</div>
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<div class="menu mainmenu">
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<ul>
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<li><a href="../index.html">Home</a>
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<li class='mobileonly'><a href="javascript:void(0)" onclick='toggle_div("submenu")'>Menu</a>
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<li class='wideonly'><a href='../about.html'>About</a>
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<li class='desktoponly'><a href="../docs.html">Documentation</a>
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<li class='desktoponly'><a href="../download.html">Download</a>
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<li class='wideonly'><a href='../copyright.html'>License</a>
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<li class='desktoponly'><a href="../support.html">Support</a>
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<li class='desktoponly'><a href="../prosupport.html">Purchase</a>
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<li class='search' id='search_menubutton'>
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<a href="javascript:void(0)" onclick='toggle_search()'>Search</a>
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</ul>
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</div>
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<div class="menu submenu" id="submenu">
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<ul>
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<li><a href='../about.html'>About</a>
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<li><a href='../docs.html'>Documentation</a>
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<li><a href='../download.html'>Download</a>
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<li><a href='../support.html'>Support</a>
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<li><a href='../prosupport.html'>Purchase</a>
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</ul>
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</div>
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<div class="searchmenu" id="searchmenu">
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<form method="GET" action="../search">
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<select name="s" id="searchtype">
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<option value="d">Search Documentation</option>
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<option value="c">Search Changelog</option>
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</select>
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<input type="text" name="q" id="searchbox" value="">
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<input type="submit" value="Go">
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</form>
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</div>
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</div>
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<script>
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function toggle_div(nm) {
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var w = document.getElementById(nm);
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if( w.style.display=="block" ){
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w.style.display = "none";
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}else{
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w.style.display = "block";
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}
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}
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function toggle_search() {
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var w = document.getElementById("searchmenu");
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if( w.style.display=="block" ){
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w.style.display = "none";
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} else {
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w.style.display = "block";
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setTimeout(function(){
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document.getElementById("searchbox").focus()
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}, 30);
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}
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}
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function div_off(nm){document.getElementById(nm).style.display="none";}
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window.onbeforeunload = function(e){div_off("submenu");}
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/* Disable the Search feature if we are not operating from CGI, since */
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/* Search is accomplished using CGI and will not work without it. */
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if( !location.origin || !location.origin.match || !location.origin.match(/http/) ){
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document.getElementById("search_menubutton").style.display = "none";
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}
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/* Used by the Hide/Show button beside syntax diagrams, to toggle the */
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function hideorshow(btn,obj){
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var x = document.getElementById(obj);
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var b = document.getElementById(btn);
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if( x.style.display!='none' ){
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x.style.display = 'none';
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b.innerHTML='show';
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}else{
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x.style.display = '';
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b.innerHTML='hide';
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}
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return false;
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}
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</script>
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</div>
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<!-- keywords: sqlite3_blob_read -->
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<div class=nosearch>
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<a href="intro.html"><h2>SQLite C Interface</h2></a>
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<h2>Read Data From A BLOB Incrementally</h2>
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</div>
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<blockquote><pre>
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int sqlite3_blob_read(sqlite3_blob *, void *Z, int N, int iOffset);
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</pre></blockquote>
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<p>
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This function is used to read data from an open <a href="../c3ref/blob.html">BLOB handle</a> into a
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caller-supplied buffer. N bytes of data are copied into buffer Z
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from the open BLOB, starting at offset iOffset.</p>
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<p>If offset iOffset is less than N bytes from the end of the BLOB,
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<a href="../rescode.html#error">SQLITE_ERROR</a> is returned and no data is read. If N or iOffset is
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less than zero, <a href="../rescode.html#error">SQLITE_ERROR</a> is returned and no data is read.
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The size of the blob (and hence the maximum value of N+iOffset)
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can be determined using the <a href="../c3ref/blob_bytes.html">sqlite3_blob_bytes()</a> interface.</p>
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<p>An attempt to read from an expired <a href="../c3ref/blob.html">BLOB handle</a> fails with an
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error code of <a href="../rescode.html#abort">SQLITE_ABORT</a>.</p>
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<p>On success, sqlite3_blob_read() returns SQLITE_OK.
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Otherwise, an <a href="../rescode.html">error code</a> or an <a href="../rescode.html#extrc">extended error code</a> is returned.</p>
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<p>This routine only works on a <a href="../c3ref/blob.html">BLOB handle</a> which has been created
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by a prior successful call to <a href="../c3ref/blob_open.html">sqlite3_blob_open()</a> and which has not
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been closed by <a href="../c3ref/blob_close.html">sqlite3_blob_close()</a>. Passing any other pointer in
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to this routine results in undefined and probably undesirable behavior.</p>
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<p>See also: <a href="../c3ref/blob_write.html">sqlite3_blob_write()</a>.
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</p><p>See also lists of
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<a href="objlist.html">Objects</a>,
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<a href="constlist.html">Constants</a>, and
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<a href="funclist.html">Functions</a>.</p>
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