<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >pg_field_is_null</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="PostgreSQL 数据库函数" HREF="ref.pgsql.html"><LINK REL="PREVIOUS" TITLE="pg_fetch_row" HREF="function.pg-fetch-row.html"><LINK REL="NEXT" TITLE="pg_field_name" HREF="function.pg-field-name.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.pg-fetch-row.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.pg-field-name.html" ACCESSKEY="N" >下一页</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="function.pg-field-is-null" ></A >pg_field_is_null</H1 ><DIV CLASS="refnamediv" ><A NAME="AEN185370" ></A ><P > (PHP 4 >= 4.2.0, PHP 5)</P >pg_field_is_null -- 测试字段是否为 <TT CLASS="constant" ><B >NULL</B ></TT ></DIV ><DIV CLASS="refsect1" ><A NAME="AEN185374" ></A ><H2 >说明</H2 >int <B CLASS="methodname" >pg_field_is_null</B > ( resource result, int row, mixed field )<BR ></BR ><P > <B CLASS="function" >pg_field_is_null()</B > 测试字段是否为 <TT CLASS="constant" ><B >NULL</B ></TT >。如果字段在给出的行中为 <TT CLASS="constant" ><B >NULL</B ></TT > 则返回 1,如果字段在给出的行中不是 <TT CLASS="constant" ><B >NULL</B ></TT > 则返回 0。字段可以以列的索引号(数字)方式给出,也可以以字段名(字符串)方式给出。行的编号从 0 开始。 </P ><P > <TABLE WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" CLASS="EXAMPLE" ><TR ><TD ><DIV CLASS="example" ><A NAME="AEN185394" ></A ><P ><B >例 1. <B CLASS="function" >pg_field_is_null()</B > 例子</B ></P ><TABLE BORDER="0" BGCOLOR="#E0E0E0" CELLPADDING="5" ><TR ><TD ><code><font color="#000000"> <font color="#0000BB"><?php<br /> $dbconn </font><font color="#007700">= </font><font color="#0000BB">pg_connect</font><font color="#007700">(</font><font color="#DD0000">"dbname=publisher"</font><font color="#007700">) or die (</font><font color="#DD0000">"Could not connect"</font><font color="#007700">);<br /> </font><font color="#0000BB">$res </font><font color="#007700">= </font><font color="#0000BB">pg_query</font><font color="#007700">(</font><font color="#0000BB">$dbconn</font><font color="#007700">, </font><font color="#DD0000">"select * from authors where author = 'Orwell'"</font><font color="#007700">);<br /> if (</font><font color="#0000BB">$res</font><font color="#007700">) {<br /> if (</font><font color="#0000BB">pg_field_is_null</font><font color="#007700">(</font><font color="#0000BB">$res</font><font color="#007700">, </font><font color="#0000BB">0</font><font color="#007700">, </font><font color="#DD0000">"year"</font><font color="#007700">) == </font><font color="#0000BB">1</font><font color="#007700">) {<br /> echo </font><font color="#DD0000">"The value of the field year is null.\n"</font><font color="#007700">;<br /> }<br /> if (</font><font color="#0000BB">pg_field_is_null</font><font color="#007700">(</font><font color="#0000BB">$res</font><font color="#007700">, </font><font color="#0000BB">0</font><font color="#007700">, </font><font color="#DD0000">"year"</font><font color="#007700">) == </font><font color="#0000BB">0</font><font color="#007700">) {<br /> echo </font><font color="#DD0000">"The value of the field year is not null.\n"</font><font color="#007700">;<br /> }<br /> }<br /></font><font color="#0000BB">?></font> </font> </code></TD ></TR ></TABLE ></DIV ></TD ></TR ></TABLE > </P ><DIV CLASS="note" ><BLOCKQUOTE CLASS="note" ><P ><B >注意: </B > 本函数以前的名字为 <TT CLASS="literal" >pg_fieldisnull()</TT >。 </P ></BLOCKQUOTE ></DIV ></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.pg-fetch-row.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.pg-field-name.html" ACCESSKEY="N" >下一页</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >pg_fetch_row</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="ref.pgsql.html" ACCESSKEY="U" >上一级</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >pg_field_name</TD ></TR ></TABLE ></DIV ></BODY ></HTML >