Sophie: php-manual-zh-5.2.4-1mdv2008.1 noarch

php-manual-zh-5.2.4-1mdv2008.1.noarch.rpm

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><H1
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>PDO-&#62;rollBack()</H1
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><P
>    (no version information, might be only in CVS)</P
>PDO-&#62;rollBack()&nbsp;--&nbsp;
   Rolls back a transaction
  </DIV
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><H2
>说明</H2
>class <B
CLASS="classname"
>PDO</B
> { <BR
></BR
>bool <B
CLASS="methodname"
>rollBack</B
> ( void  )<BR
></BR
>}<P
>&#13;   Rolls back the current transaction, as initiated by
   <A
HREF="function.pdo-begintransaction.html"
>PDO-&#62;beginTransaction()</A
>.  It is an error to call this
   method if no transaction is active.
  </P
><P
>&#13;   If the database was set to autocommit mode, this function will restore
   autocommit mode after it has rolled back the transaction.
  </P
><P
>&#13;   Some databases, including MySQL, automatically issue an implicit
   COMMIT when a database definition language (DDL) statement such as
   DROP TABLE or CREATE TABLE is issued within a transaction. The implicit
   COMMIT will prevent you from rolling back any other changes within the
   transaction boundary.
  </P
></DIV
><DIV
CLASS="refsect1"
><A
NAME="AEN177021"
></A
><H2
>返回值</H2
><P
>&#13;   如果成功则返回 <TT
CLASS="constant"
><B
>TRUE</B
></TT
>，失败则返回 <TT
CLASS="constant"
><B
>FALSE</B
></TT
>。
  </P
></DIV
><DIV
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><A
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></A
><H2
>范例</H2
><P
>&#13;   <TABLE
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><P
><B
>例 1. Roll back a transaction</B
></P
><P
>&#13;     The following example begins a transaction and issues two statements
     that modify the database before rolling back the changes. On MySQL,
     however, the DROP TABLE statement automatically commits the
     transaction so that none of the changes in the transaction are rolled
     back.
    </P
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><code><font color="#000000">
<font color="#0000BB">&lt;?php<br /></font><font color="#FF8000">/* Begin a transaction, turning off autocommit */<br /></font><font color="#0000BB">$dbh</font><font color="#007700">-&gt;</font><font color="#0000BB">beginTransaction</font><font color="#007700">();<br /><br /></font><font color="#FF8000">/* Change the database schema and data */<br /></font><font color="#0000BB">$sth </font><font color="#007700">= </font><font color="#0000BB">$dbh</font><font color="#007700">-&gt;</font><font color="#0000BB">exec</font><font color="#007700">(</font><font color="#DD0000">"DROP TABLE fruit"</font><font color="#007700">);<br /></font><font color="#0000BB">$sth </font><font color="#007700">= </font><font color="#0000BB">$dbh</font><font color="#007700">-&gt;</font><font color="#0000BB">exec</font><font color="#007700">(</font><font color="#DD0000">"UPDATE dessert<br />&nbsp;&nbsp;&nbsp;&nbsp;SET name = 'hamburger'"</font><font color="#007700">);<br /><br /></font><font color="#FF8000">/* Recognize mistake and roll back changes */<br /></font><font color="#0000BB">$dbh</font><font color="#007700">-&gt;</font><font color="#0000BB">rollBack</font><font color="#007700">();<br /><br /></font><font color="#FF8000">/* Database connection is now back in autocommit mode */<br /></font><font color="#0000BB">?&gt;</font>
</font>
</code></TD
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>
  </P
></DIV
><DIV
CLASS="refsect1"
><A
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></A
><H2
>参见</H2
><P
>&#13;   <P
></P
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><A
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>PDO-&#62;beginTransaction()</A
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><A
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>PDO-&#62;commit()</A
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