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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"><html><head><title>Open A BLOB For Incremental I/O</title><style type="text/css">body { margin: auto; font-family: "Verdana" "sans-serif"; padding: 8px 1%;}a { color: #45735f }a:visited { color: #734559 }.logo { position:absolute; margin:3px; }.tagline { float:right; text-align:right; font-style:italic; width:240px; margin:12px; margin-top:58px;}.toolbar { font-variant: small-caps; text-align: center; line-height: 1.6em; margin: 0; padding:1px 8px;}.toolbar a { color: white; text-decoration: none; padding: 6px 12px; }.toolbar a:visited { color: white; }.toolbar a:hover { color: #80a796; background: white; }.content { margin: 5%; }.content dt { font-weight:bold; }.content dd { margin-bottom: 25px; margin-left:20%; }.content ul { padding:0px; padding-left: 15px; margin:0px; }/* rounded corners */.se { background: url(../images/se.png) 100% 100% no-repeat #80a796}.sw { background: url(../images/sw.png) 0% 100% no-repeat }.ne { background: url(../images/ne.png) 100% 0% no-repeat }.nw { background: url(../images/nw.png) 0% 0% no-repeat }</style><meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head><body><div><!-- container div to satisfy validator --><a href="../index.html"><img class="logo" src="../images/SQLite.gif" alt="SQLite Logo" border="0"></a><div><!-- IE hack to prevent disappearing logo--></div><div class="tagline">Small. Fast. Reliable.<br>Choose any three.</div><table width=100% style="clear:both"><tr><td> <div class="se"><div class="sw"><div class="ne"><div class="nw"> <div class="toolbar"> <a href="../about.html">About</a> <a href="../sitemap.html">Sitemap</a> <a href="../docs.html">Documentation</a> <a href="../download.html">Download</a> <a href="../copyright.html">License</a> <a href="../news.html">News</a> <a href="http://www.sqlite.org/cvstrac/index">Developers</a> <a href="../support.html">Support</a> </div></div></div></div></div></td></tr></table> <a href="intro.html"><h2>SQLite C Interface</h2></a><h2>Open A BLOB For Incremental I/O</h2><blockquote><pre>int sqlite3_blob_open( sqlite3*, const char *zDb, const char *zTable, const char *zColumn, sqlite3_int64 iRow, int flags, sqlite3_blob **ppBlob);</pre></blockquote><p>This interfaces opens a handle to the blob locatedin row iRow, column zColumn, table zTable in database zDb;in other words, the same blob that would be selected by:</p><p><pre>SELECT zColumn FROM zDb.zTable WHERE rowid = iRow;</pre></p><p>If the flags parameter is non-zero, the blob is opened forread and write access. If it is zero, the blob is opened for readaccess.</p><p>Note that the database name is not the filename that containsthe database but rather the symbolic name of the database thatis assigned when the database is connected using <a href="../lang_attach.html">ATTACH</a>.For the main database file, the database name is "main". ForTEMP tables, the database name is "temp".</p><p>On success, <a href="../c3ref/c_abort.html">SQLITE_OK</a> is returned and the new<a href="../c3ref/blob.html">blob handle</a> is written to *ppBlob.Otherwise an error code is returned andany value written to *ppBlob should not be used by the caller.This function sets the database-handle error code and messageaccessible via <a href="../c3ref/errcode.html">sqlite3_errcode()</a> and <a href="../c3ref/errcode.html">sqlite3_errmsg()</a>.</p><p><h3>Invariants:</h3><table border="0" cellpadding="5" cellspacing="0"><tr><td valign="top">F17813</td> <td valign="top">A successful invocation of the <a href="../c3ref/blob_open.html">sqlite3_blob_open(D,B,T,C,R,F,P)</a>interface opens an <a href="../c3ref/blob.html">sqlite3_blob</a> object P on the blobin column C of table T in database B on <a href="../c3ref/sqlite3.html">database connection</a> D.</td></tr><tr><td valign="top">F17814</td> <td valign="top">A successful invocation of <a href="../c3ref/blob_open.html">sqlite3_blob_open(D,...)</a> startsa new transaction on <a href="../c3ref/sqlite3.html">database connection</a> D if that connectionis not already in a transaction.</td></tr><tr><td valign="top">F17816</td> <td valign="top">The <a href="../c3ref/blob_open.html">sqlite3_blob_open(D,B,T,C,R,F,P)</a> interface opens the blobfor read and write access if and only if the F parameteris non-zero.</td></tr><tr><td valign="top">F17819</td> <td valign="top">The <a href="../c3ref/blob_open.html">sqlite3_blob_open()</a> interface returns <a href="../c3ref/c_abort.html">SQLITE_OK</a> onsuccess and an appropriate <a href="../c3ref/c_abort.html">error code</a> on failure.</td></tr><tr><td valign="top">F17821</td> <td valign="top">If an error occurs during evaluation of <a href="../c3ref/blob_open.html">sqlite3_blob_open(D,...)</a>then subsequent calls to <a href="../c3ref/errcode.html">sqlite3_errcode(D)</a>,<a href="../c3ref/errcode.html">sqlite3_errmsg(D)</a>, and <a href="../c3ref/errcode.html">sqlite3_errmsg16(D)</a> will returninformation approprate for that error.</td></tr></table></p><p>See also lists of <a href="objlist.html">Objects</a>, <a href="constlist.html">Constants</a>, and <a href="funclist.html">Functions</a>.</p><hr><small><i>This page last modified 2008/02/21 17:46:11 UTC</i></small></div></body></html>⌨️ 快捷键说明
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