<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >sqlite_create_function</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REL="HOME" TITLE="PHP 手册" HREF="index.html"><LINK REL="UP" TITLE="SQLite Functions" HREF="ref.sqlite.html"><LINK REL="PREVIOUS" TITLE="sqlite_create_aggregate" HREF="function.sqlite-create-aggregate.html"><LINK REL="NEXT" TITLE="sqlite_current" HREF="function.sqlite-current.html"><META HTTP-EQUIV="Content-type" CONTENT="text/html; charset=UTF-8"></HEAD ><BODY CLASS="refentry" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >PHP 手册</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="function.sqlite-create-aggregate.html" ACCESSKEY="P" >上一页</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="function.sqlite-current.html" ACCESSKEY="N" >下一页</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="function.sqlite-create-function" ></A >sqlite_create_function</H1 ><DIV CLASS="refnamediv" ><A NAME="AEN216193" ></A ><P > (PHP 5)</P >sqlite_create_function<P > (no version information, might be only in CVS)</P >SQLiteDatabase->createFunction -- Registers a "regular" User Defined Function for use in SQL statements </DIV ><DIV CLASS="refsect1" ><A NAME="AEN216197" ></A ><H2 >说明</H2 >void <B CLASS="methodname" >sqlite_create_function</B > ( resource dbhandle, string function_name, callback callback [, int num_args] )<BR ></BR ><P >Object oriented style (method):</P >class <B CLASS="classname" >SQLiteDatabase</B > { <BR ></BR >void <B CLASS="methodname" >createFunction</B > ( string function_name, callback callback [, int num_args] )<BR ></BR >}<P > <B CLASS="function" >sqlite_create_function()</B > allows you to register a PHP function with SQLite as an <ACRONYM CLASS="acronym" >UDF</ACRONYM > (User Defined Function), so that it can be called from within your SQL statements. </P ><P > The UDF can be used in any SQL statement that can call functions, such as SELECT and UPDATE statements and also in triggers. </P ></DIV ><DIV CLASS="refsect1" ><A NAME="AEN216234" ></A ><H2 >参数</H2 ><P > <P ></P ><DIV CLASS="variablelist" ><DL ><DT ><CODE CLASS="parameter" >dbhandle</CODE ></DT ><DD ><P > The SQLite Database resource; returned from <A HREF="function.sqlite-open.html" ><B CLASS="function" >sqlite_open()</B ></A > when used procedurally. This parameter is not required when using the object-oriented method. </P ></DD ><DT ><CODE CLASS="parameter" >function_name</CODE ></DT ><DD ><P > The name of the function used in SQL statements. </P ></DD ><DT ><CODE CLASS="parameter" >callback</CODE ></DT ><DD ><P > Callback function to handle the defined SQL function. </P ><DIV CLASS="note" ><BLOCKQUOTE CLASS="note" ><P ><B >注意: </B > Callback functions should return a type understood by SQLite (i.e. <A HREF="language.types.html#language.types.intro" >scalar type</A >). </P ></BLOCKQUOTE ></DIV ></DD ><DT ><CODE CLASS="parameter" >num_args</CODE ></DT ><DD ><P > Hint to the SQLite parser if the callback function accepts a predetermined number of arguments. </P ></DD ></DL ></DIV > </P ><DIV CLASS="note" ><BLOCKQUOTE CLASS="note" ><P ><B >注意: </B >为兼容其它数据库(例如 MySQL),支持另两种替代的语法。推荐用第一种,<CODE CLASS="parameter" >dbhandle</CODE > 参数作为函数的第一个参数。</P ></BLOCKQUOTE ></DIV ></DIV ><DIV CLASS="refsect1" ><A NAME="AEN216265" ></A ><H2 >返回值</H2 ><P > 无返回值。 </P ></DIV ><DIV CLASS="refsect1" ><A NAME="AEN216268" ></A ><H2 >范例</H2 ><P > <TABLE WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" CLASS="EXAMPLE" ><TR ><TD ><DIV CLASS="example" ><A NAME="AEN216271" ></A ><P ><B >例 1. <B CLASS="function" >sqlite_create_function()</B > example</B ></P ><TABLE BORDER="0" BGCOLOR="#E0E0E0" CELLPADDING="5" ><TR ><TD ><code><font color="#000000"> <font color="#0000BB"><?php<br /></font><font color="#007700">function </font><font color="#0000BB">md5_and_reverse</font><font color="#007700">(</font><font color="#0000BB">$string</font><font color="#007700">) <br />{<br /> return </font><font color="#0000BB">strrev</font><font color="#007700">(</font><font color="#0000BB">md5</font><font color="#007700">(</font><font color="#0000BB">$string</font><font color="#007700">));<br />}<br /><br />if (</font><font color="#0000BB">$dbhandle </font><font color="#007700">= </font><font color="#0000BB">sqlite_open</font><font color="#007700">(</font><font color="#DD0000">'mysqlitedb'</font><font color="#007700">, </font><font color="#0000BB">0666</font><font color="#007700">, </font><font color="#0000BB">$sqliteerror</font><font color="#007700">)) {<br /> <br /> </font><font color="#0000BB">sqlite_create_function</font><font color="#007700">(</font><font color="#0000BB">$dbhandle</font><font color="#007700">, </font><font color="#DD0000">'md5rev'</font><font color="#007700">, </font><font color="#DD0000">'md5_and_reverse'</font><font color="#007700">, </font><font color="#0000BB">1</font><font color="#007700">);<br /> <br /> </font><font color="#0000BB">$sql </font><font color="#007700">= </font><font color="#DD0000">'SELECT md5rev(filename) FROM files'</font><font color="#007700">;<br /> </font><font color="#0000BB">$rows </font><font color="#007700">= </font><font color="#0000BB">sqlite_array_query</font><font color="#007700">(</font><font color="#0000BB">$dbhandle</font><font color="#007700">, </font><font color="#0000BB">$sql</font><font color="#007700">);<br />} else {<br /> echo </font><font color="#DD0000">'Error opening sqlite db: ' </font><font color="#007700">. </font><font color="#0000BB">$sqliteerror</font><font color="#007700">;<br /> exit;<br />}<br /></font><font color="#0000BB">?></font> </font> </code></TD ></TR ></TABLE ></DIV ></TD ></TR ></TABLE > </P ><P > In this example, we have a function that calculates the md5 sum of a string, and then reverses it. When the SQL statement executes, it returns the value of the filename transformed by our function. The data returned in <CODE CLASS="parameter" >$rows</CODE > contains the processed result. </P ><P > The beauty of this technique is that you do not need to process the result using a foreach() loop after you have queried for the data. </P ><P > PHP registers a special function named <TT CLASS="literal" >php</TT > when the database is first opened. The php function can be used to call any PHP function without having to register it first. </P ><P > <TABLE WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" CLASS="EXAMPLE" ><TR ><TD ><DIV CLASS="example" ><A NAME="AEN216281" ></A ><P ><B >例 2. Example of using the PHP function</B ></P ><TABLE BORDER="0" BGCOLOR="#E0E0E0" CELLPADDING="5" ><TR ><TD ><code><font color="#000000"> <font color="#0000BB"><?php<br />$rows </font><font color="#007700">= </font><font color="#0000BB">sqlite_array_query</font><font color="#007700">(</font><font color="#0000BB">$dbhandle</font><font color="#007700">, </font><font color="#DD0000">"SELECT php('md5', filename) from files"</font><font color="#007700">);<br /></font><font color="#0000BB">?></font> </font> </code></TD ></TR ></TABLE ><P > This example will call the <A HREF="function.md5.html" ><B CLASS="function" >md5()</B ></A > on each <TT CLASS="literal" >filename</TT > column in the database and return the result into <CODE CLASS="parameter" >$rows</CODE > </P ></DIV ></TD ></TR ></TABLE > </P ><DIV CLASS="note" ><BLOCKQUOTE CLASS="note" ><P ><B >注意: </B > For performance reasons, PHP will not automatically encode/decode binary data passed to and from your UDF's. You need to manually encode/decode the parameters and return values if you need to process binary data in this way. Take a look at <A HREF="function.sqlite-udf-encode-binary.html" ><B CLASS="function" >sqlite_udf_encode_binary()</B ></A > and <A HREF="function.sqlite-udf-decode-binary.html" ><B CLASS="function" >sqlite_udf_decode_binary()</B ></A > for more details. </P ></BLOCKQUOTE ></DIV ><DIV CLASS="tip" ><BLOCKQUOTE CLASS="tip" ><P ><B >提示: </B > It is not recommended to use UDF's to handle processing of binary data, unless high performance is not a key requirement of your application. </P ></BLOCKQUOTE ></DIV ><DIV CLASS="tip" ><BLOCKQUOTE CLASS="tip" ><P ><B >提示: </B > You can use <B CLASS="function" >sqlite_create_function()</B > and <A HREF="function.sqlite-create-aggregate.html" ><B CLASS="function" >sqlite_create_aggregate()</B ></A > to override SQLite native SQL functions. </P ></BLOCKQUOTE ></DIV ></DIV ><DIV CLASS="refsect1" ><A NAME="AEN216298" ></A ><H2 >参见</H2 ><P > <P ></P ><TABLE BORDER="0" ><TBODY ><TR ><TD ><A HREF="function.sqlite-create-aggregate.html" ><B CLASS="function" >sqlite_create_aggregate()</B ></A ></TD ></TR ></TBODY ></TABLE ><P ></P > </P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="function.sqlite-create-aggregate.html" ACCESSKEY="P" >上一页</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >起始页</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="function.sqlite-current.html" ACCESSKEY="N" >下一页</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >sqlite_create_aggregate</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="ref.sqlite.html" ACCESSKEY="U" >上一级</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >sqlite_current</TD ></TR ></TABLE ></DIV ></BODY ></HTML >