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>pg_field_is_null</H1
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><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。
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><B
>例 1. <B
CLASS="function"
>pg_field_is_null()</B
> 例子</B
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><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>
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><P
><B
>注意: </B
>
本函数以前的名字为 <TT
CLASS="literal"
>pg_fieldisnull()</TT
>。
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