archived-doc-zh/reference/pgsql/functions/pg-send-query.xml

<?xml version="1.0" encoding="utf-8"?>
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<!-- EN-Revision: c2eca73ef79ebe78cebb34053e41b565af504c4f Maintainer: dallas Status: ready -->
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<!-- splitted from ./en/functions/pgsql.xml, last change in rev 1.2 -->
<refentry xml:id="function.pg-send-query" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>pg_send_query</refname>
  <refpurpose>
   发送异步查询
  </refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type class="union"><type>int</type><type>bool</type></type><methodname>pg_send_query</methodname>
   <methodparam><type>PgSql\Connection</type><parameter>connection</parameter></methodparam>
   <methodparam><type>string</type><parameter>query</parameter></methodparam>
  </methodsynopsis>
  <para>
   <function>pg_send_query</function> 向 <parameter>connection</parameter> 发送异步查询。跟 <function>pg_query</function>
   不同，它可以一次性向 PostgreSQL 发送多个查询并用 <function>pg_get_result</function> 依次得到结果。
  </para>
  <para>
   当执行查询时不会阻塞脚本执行。用 <function>pg_connection_busy</function> 来检查连接是否繁忙（即查询正在执行中）。可以使用
   <function>pg_cancel_query</function> 取消查询。
  </para>
  <para>
   尽管用户可以同时发送多个查询，但连接繁忙的情况下无法发送多个查询。如果连接繁忙时发送了查询，则会等待上一个查询结束，并且丢弃上个查询的所有结果。
  </para>
 </refsect1>
 
 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>connection</parameter></term>
     <listitem>
      &pgsql.parameter.connection;
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>query</parameter></term>
     <listitem>
      <para>
       要执行的 SQL 语句或者语句集合。
      </para>
      <para>
       应该<link linkend="function.pg-escape-string">正确转义</link>查询中的数据。
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   成功时返回 &true;，失败时返回 &false; 或 <literal>0</literal>。使用 <function>pg_get_result</function>
   来确定查询结果。
  </para>
 </refsect1>

 <refsect1 role="changelog">
  &reftitle.changelog;
  <informaltable>
   <tgroup cols="2">
    <thead>
     <row>
      <entry>&Version;</entry>
      <entry>&Description;</entry>
     </row>
    </thead>
    <tbody>
     &pgsql.changelog.connection-object;
    </tbody>
   </tgroup>
  </informaltable>
 </refsect1>
 
 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>pg_send_query</function> 示例</title>
    <programlisting role="php">
<![CDATA[
<?php
  $dbconn = pg_connect("dbname=publisher") or die("Could not connect");

  if (!pg_connection_busy($dbconn)) {
      pg_send_query($dbconn, "select * from authors; select count(*) from authors;");
  }
  
  $res1 = pg_get_result($dbconn);
  echo "First call to pg_get_result(): $res1\n";
  $rows1 = pg_num_rows($res1);
  echo "$res1 has $rows1 records\n\n";
  
  $res2 = pg_get_result($dbconn);
  echo "Second call to pg_get_result(): $res2\n";
  $rows2 = pg_num_rows($res2);
  echo "$res2 has $rows2 records\n";
?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
First call to pg_get_result(): Resource id #3
Resource id #3 has 3 records

Second call to pg_get_result(): Resource id #4
Resource id #4 has 1 records
]]>
    </screen>
   </example> 
  </para>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>pg_query</function></member>
    <member><function>pg_cancel_query</function></member>
    <member><function>pg_get_result</function></member>
    <member><function>pg_connection_busy</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>
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