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| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-05 17:28:19 +0000 |
|---|---|---|
| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-05 17:28:19 +0000 |
| commit | 18657a960e125336f704ea058e25c27bd3900dcb (patch) | |
| tree | 17b438b680ed45a996d7b59951e6aa34023783f2 /www/c3ref/value_blob.html | |
| parent | Initial commit. (diff) | |
| download | sqlite3-upstream.tar.xz sqlite3-upstream.zip | |
Adding upstream version 3.40.1.upstream/3.40.1upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
| -rw-r--r-- | www/c3ref/value_blob.html | 279 |
1 files changed, 279 insertions, 0 deletions
diff --git a/www/c3ref/value_blob.html b/www/c3ref/value_blob.html new file mode 100644 index 0000000..4478b95 --- /dev/null +++ b/www/c3ref/value_blob.html @@ -0,0 +1,279 @@ +<!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>Obtaining SQL Values</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> +<!-- keywords: sqlite3_value_blob sqlite3_value_bytes sqlite3_value_bytes16 sqlite3_value_double sqlite3_value_encoding sqlite3_value_frombind sqlite3_value_int sqlite3_value_int64 sqlite3_value_nochange sqlite3_value_numeric_type sqlite3_value_pointer sqlite3_value_text sqlite3_value_text16 sqlite3_value_text16be sqlite3_value_text16le sqlite3_value_type --> +<div class=nosearch> +<a href="intro.html"><h2>SQLite C Interface</h2></a> +<h2>Obtaining SQL Values</h2> +</div> +<blockquote><pre> +const void *sqlite3_value_blob(sqlite3_value*); +double sqlite3_value_double(sqlite3_value*); +int sqlite3_value_int(sqlite3_value*); +sqlite3_int64 sqlite3_value_int64(sqlite3_value*); +void *sqlite3_value_pointer(sqlite3_value*, const char*); +const unsigned char *sqlite3_value_text(sqlite3_value*); +const void *sqlite3_value_text16(sqlite3_value*); +const void *sqlite3_value_text16le(sqlite3_value*); +const void *sqlite3_value_text16be(sqlite3_value*); +int sqlite3_value_bytes(sqlite3_value*); +int sqlite3_value_bytes16(sqlite3_value*); +int sqlite3_value_type(sqlite3_value*); +int sqlite3_value_numeric_type(sqlite3_value*); +int sqlite3_value_nochange(sqlite3_value*); +int sqlite3_value_frombind(sqlite3_value*); +int sqlite3_value_encoding(sqlite3_value*); +</pre></blockquote> +<p> +<b>Summary:</b> +<blockquote><table border=0 cellpadding=0 cellspacing=0> +<tr><td><b>sqlite3_value_blob</b><td>→<td>BLOB value +<tr><td><b>sqlite3_value_double</b><td>→<td>REAL value +<tr><td><b>sqlite3_value_int</b><td>→<td>32-bit INTEGER value +<tr><td><b>sqlite3_value_int64</b><td>→<td>64-bit INTEGER value +<tr><td><b>sqlite3_value_pointer</b><td>→<td>Pointer value +<tr><td><b>sqlite3_value_text</b><td>→<td>UTF-8 TEXT value +<tr><td><b>sqlite3_value_text16</b><td>→<td>UTF-16 TEXT value in +the native byteorder +<tr><td><b>sqlite3_value_text16be</b><td>→<td>UTF-16be TEXT value +<tr><td><b>sqlite3_value_text16le</b><td>→<td>UTF-16le TEXT value +<tr><td> <td> <td> +<tr><td><b>sqlite3_value_bytes</b><td>→<td>Size of a BLOB +or a UTF-8 TEXT in bytes +<tr><td><b>sqlite3_value_bytes16 </b> +<td>→ <td>Size of UTF-16 +TEXT in bytes +<tr><td><b>sqlite3_value_type</b><td>→<td>Default +datatype of the value +<tr><td><b>sqlite3_value_numeric_type </b> +<td>→ <td>Best numeric datatype of the value +<tr><td><b>sqlite3_value_nochange </b> +<td>→ <td>True if the column is unchanged in an UPDATE +against a virtual table. +<tr><td><b>sqlite3_value_frombind </b> +<td>→ <td>True if value originated from a <a href="../lang_expr.html#varparam">bound parameter</a> +</table></blockquote></p> + +<p><b>Details:</b></p> + +<p>These routines extract type, size, and content information from +<a href="../c3ref/value.html">protected sqlite3_value</a> objects. Protected sqlite3_value objects +are used to pass parameter information into the functions that +implement <a href="../appfunc.html">application-defined SQL functions</a> and <a href="../vtab.html">virtual tables</a>.</p> + +<p>These routines work only with <a href="../c3ref/value.html">protected sqlite3_value</a> objects. +Any attempt to use these routines on an <a href="../c3ref/value.html">unprotected sqlite3_value</a> +is not threadsafe.</p> + +<p>These routines work just like the corresponding <a href="../c3ref/column_blob.html">column access functions</a> +except that these routines take a single <a href="../c3ref/value.html">protected sqlite3_value</a> object +pointer instead of a <a href="../c3ref/stmt.html">sqlite3_stmt*</a> pointer and an integer column number.</p> + +<p>The sqlite3_value_text16() interface extracts a UTF-16 string +in the native byte-order of the host machine. The +sqlite3_value_text16be() and sqlite3_value_text16le() interfaces +extract UTF-16 strings as big-endian and little-endian respectively.</p> + +<p>If <a href="../c3ref/value.html">sqlite3_value</a> object V was initialized +using <a href="../c3ref/bind_blob.html">sqlite3_bind_pointer(S,I,P,X,D)</a> or <a href="../c3ref/result_blob.html">sqlite3_result_pointer(C,P,X,D)</a> +and if X and Y are strings that compare equal according to strcmp(X,Y), +then sqlite3_value_pointer(V,Y) will return the pointer P. Otherwise, +sqlite3_value_pointer(V,Y) returns a NULL. The sqlite3_bind_pointer() +routine is part of the <a href="../bindptr.html">pointer passing interface</a> added for SQLite 3.20.0.</p> + +<p>The sqlite3_value_type(V) interface returns the +<a href="../c3ref/c_blob.html">datatype code</a> for the initial datatype of the +<a href="../c3ref/value.html">sqlite3_value</a> object V. The returned value is one of <a href="../c3ref/c_blob.html">SQLITE_INTEGER</a>, +<a href="../c3ref/c_blob.html">SQLITE_FLOAT</a>, <a href="../c3ref/c_blob.html">SQLITE_TEXT</a>, <a href="../c3ref/c_blob.html">SQLITE_BLOB</a>, or <a href="../c3ref/c_blob.html">SQLITE_NULL</a>. +Other interfaces might change the datatype for an sqlite3_value object. +For example, if the datatype is initially SQLITE_INTEGER and +sqlite3_value_text(V) is called to extract a text value for that +integer, then subsequent calls to sqlite3_value_type(V) might return +SQLITE_TEXT. Whether or not a persistent internal datatype conversion +occurs is undefined and may change from one release of SQLite to the next.</p> + +<p>The sqlite3_value_numeric_type() interface attempts to apply +numeric affinity to the value. This means that an attempt is +made to convert the value to an integer or floating point. If +such a conversion is possible without loss of information (in other +words, if the value is a string that looks like a number) +then the conversion is performed. Otherwise no conversion occurs. +The <a href="../c3ref/c_blob.html">datatype</a> after conversion is returned.</p> + +<p>The sqlite3_value_encoding(X) interface returns one of <a href="../c3ref/c_any.html">SQLITE_UTF8</a>, +<a href="../c3ref/c_any.html">SQLITE_UTF16BE</a>, or <a href="../c3ref/c_any.html">SQLITE_UTF16LE</a> according to the current encoding +of the value X, assuming that X has type TEXT. If sqlite3_value_type(X) +returns something other than SQLITE_TEXT, then the return value from +sqlite3_value_encoding(X) is meaningless. Calls to +sqlite3_value_text(X), sqlite3_value_text16(X), sqlite3_value_text16be(X), +sqlite3_value_text16le(X), sqlite3_value_bytes(X), or +sqlite3_value_bytes16(X) might change the encoding of the value X and +thus change the return from subsequent calls to sqlite3_value_encoding(X).</p> + +<p>Within the <a href="../vtab.html#xupdate">xUpdate</a> method of a <a href="../vtab.html">virtual table</a>, the +sqlite3_value_nochange(X) interface returns true if and only if +the column corresponding to X is unchanged by the UPDATE operation +that the xUpdate method call was invoked to implement and if +and the prior <a href="../vtab.html#xcolumn">xColumn</a> method call that was invoked to extracted +the value for that column returned without setting a result (probably +because it queried <a href="../c3ref/vtab_nochange.html">sqlite3_vtab_nochange()</a> and found that the column +was unchanging). Within an <a href="../vtab.html#xupdate">xUpdate</a> method, any value for which +sqlite3_value_nochange(X) is true will in all other respects appear +to be a NULL value. If sqlite3_value_nochange(X) is invoked anywhere other +than within an <a href="../vtab.html#xupdate">xUpdate</a> method call for an UPDATE statement, then +the return value is arbitrary and meaningless.</p> + +<p>The sqlite3_value_frombind(X) interface returns non-zero if the +value X originated from one of the <a href="../c3ref/bind_blob.html">sqlite3_bind()</a> +interfaces. If X comes from an SQL literal value, or a table column, +or an expression, then sqlite3_value_frombind(X) returns zero.</p> + +<p>Please pay particular attention to the fact that the pointer returned +from <a href="../c3ref/value_blob.html">sqlite3_value_blob()</a>, <a href="../c3ref/value_blob.html">sqlite3_value_text()</a>, or +<a href="../c3ref/value_blob.html">sqlite3_value_text16()</a> can be invalidated by a subsequent call to +<a href="../c3ref/value_blob.html">sqlite3_value_bytes()</a>, <a href="../c3ref/value_blob.html">sqlite3_value_bytes16()</a>, <a href="../c3ref/value_blob.html">sqlite3_value_text()</a>, +or <a href="../c3ref/value_blob.html">sqlite3_value_text16()</a>.</p> + +<p>These routines must be called from the same thread as +the SQL function that supplied the <a href="../c3ref/value.html">sqlite3_value*</a> parameters.</p> + +<p>As long as the input parameter is correct, these routines can only +fail if an out-of-memory error occurs during a format conversion. +Only the following subset of interfaces are subject to out-of-memory +errors:</p> + +<p><ul> +<li> sqlite3_value_blob() +<li> sqlite3_value_text() +<li> sqlite3_value_text16() +<li> sqlite3_value_text16le() +<li> sqlite3_value_text16be() +<li> sqlite3_value_bytes() +<li> sqlite3_value_bytes16() +</ul></p> + +<p>If an out-of-memory error occurs, then the return value from these +routines is the same as if the column had contained an SQL NULL value. +Valid SQL NULL returns can be distinguished from out-of-memory errors +by invoking the <a href="../c3ref/errcode.html">sqlite3_errcode()</a> immediately after the suspect +return value is obtained and before any +other SQLite interface is called on the same <a href="../c3ref/sqlite3.html">database connection</a>. +</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> + |