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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"><html><head><title>Source Of Data In A Query Result</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>Source Of Data In A Query Result</h2><blockquote><pre>const char *sqlite3_column_database_name(sqlite3_stmt*,int);const void *sqlite3_column_database_name16(sqlite3_stmt*,int);const char *sqlite3_column_table_name(sqlite3_stmt*,int);const void *sqlite3_column_table_name16(sqlite3_stmt*,int);const char *sqlite3_column_origin_name(sqlite3_stmt*,int);const void *sqlite3_column_origin_name16(sqlite3_stmt*,int);</pre></blockquote><p>These routines provide a means to determine what column of whattable in which database a result of a SELECT statement comes from.The name of the database or table or column can be returned aseither a UTF8 or UTF16 string. The _database_ routines returnthe database name, the _table_ routines return the table name, andthe origin_ routines return the column name.The returned string is valid untilthe <a href="../c3ref/stmt.html">prepared statement</a> is destroyed using<a href="../c3ref/finalize.html">sqlite3_finalize()</a> or until the same information is requestedagain in a different encoding.</p><p>The names returned are the original un-aliased names of thedatabase, table, and column.</p><p>The first argument to the following calls is a <a href="../c3ref/stmt.html">prepared statement</a>.These functions return information about the Nth column returned bythe statement, where N is the second function argument.</p><p>If the Nth column returned by the statement is an expressionor subquery and is not a column value, then all of these functionsreturn NULL. These routine might also return NULL if a memoryallocation error occurs. Otherwise, they return thename of the attached database, table and column that query resultcolumn was extracted from.</p><p>As with all other SQLite APIs, those postfixed with "16" returnUTF-16 encoded strings, the other functions return UTF-8.</p><p>These APIs are only available if the library was compiled with theSQLITE_ENABLE_COLUMN_METADATA preprocessor symbol defined.</p><p>If two or more threads call one or more of these routines against the sameprepared statement and column at the same time then the results areundefined.</p><p><h3>Invariants:</h3><table border="0" cellpadding="5" cellspacing="0"><tr><td valign="top">F13741</td> <td valign="top">The <a href="../c3ref/column_database_name.html">sqlite3_column_database_name(S,N)</a> interface returns eitherthe UTF-8 zero-terminated name of the database from which theNth result column of <a href="../c3ref/stmt.html">prepared statement</a> Sis extracted, or NULL if the the Nth column of S is ageneral expression or if unable to allocate memoryto store the name.</td></tr><tr><td valign="top">F13742</td> <td valign="top">The <a href="../c3ref/column_database_name.html">sqlite3_column_database_name16(S,N)</a> interface returns eitherthe UTF-16 native byte orderzero-terminated name of the database from which theNth result column of <a href="../c3ref/stmt.html">prepared statement</a> Sis extracted, or NULL if the the Nth column of S is ageneral expression or if unable to allocate memoryto store the name.</td></tr><tr><td valign="top">F13743</td> <td valign="top">The <a href="../c3ref/column_database_name.html">sqlite3_column_table_name(S,N)</a> interface returns eitherthe UTF-8 zero-terminated name of the table from which theNth result column of <a href="../c3ref/stmt.html">prepared statement</a> Sis extracted, or NULL if the the Nth column of S is ageneral expression or if unable to allocate memoryto store the name.</td></tr><tr><td valign="top">F13744</td> <td valign="top">The <a href="../c3ref/column_database_name.html">sqlite3_column_table_name16(S,N)</a> interface returns eitherthe UTF-16 native byte orderzero-terminated name of the table from which theNth result column of <a href="../c3ref/stmt.html">prepared statement</a> Sis extracted, or NULL if the the Nth column of S is ageneral expression or if unable to allocate memoryto store the name.</td></tr><tr><td valign="top">F13745</td> <td valign="top">The <a href="../c3ref/column_database_name.html">sqlite3_column_origin_name(S,N)</a> interface returns eitherthe UTF-8 zero-terminated name of the table column from which theNth result column of <a href="../c3ref/stmt.html">prepared statement</a> Sis extracted, or NULL if the the Nth column of S is ageneral expression or if unable to allocate memoryto store the name.</td></tr><tr><td valign="top">F13746</td> <td valign="top">The <a href="../c3ref/column_database_name.html">sqlite3_column_origin_name16(S,N)</a> interface returns eitherthe UTF-16 native byte orderzero-terminated name of the table column from which theNth result column of <a href="../c3ref/stmt.html">prepared statement</a> Sis extracted, or NULL if the the Nth column of S is ageneral expression or if unable to allocate memoryto store the name.</td></tr><tr><td valign="top">F13748</td> <td valign="top">The return values from<a href="../c3ref/column_database_name.html">column metadata interfaces</a>are validfor the lifetime of the <a href="../c3ref/stmt.html">prepared statement</a>or until the encoding is changed by another metadatainterface call for the same prepared statement and column.</td></tr></table></p><p><h3>Limitations:</h3><table border="0" cellpadding="5" cellspacing="0"><tr><td valign="top">U13751</td> <td valign="top">If two or more threads call one or more<a href="../c3ref/column_database_name.html">column metadata interfaces</a>the same <a href="../c3ref/stmt.html">prepared statement</a> and result columnat the same time then the results are undefined.</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 2008/05/12 13:08:44 UTC</i></small></div></body></html>⌨️ 快捷键说明
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