start_transaction.sgml

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

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$PostgreSQL: pgsql/doc/src/sgml/ref/start_transaction.sgml,v 1.14 2004/09/20 00:04:19 neilc Exp $
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<refentry id="SQL-START-TRANSACTION">
 <refmeta>
  <refentrytitle id="SQL-START-TRANSACTION-TITLE">START TRANSACTION</refentrytitle>
  <refmiscinfo>SQL - Language Statements</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>START TRANSACTION</refname>
  <refpurpose>start a transaction block</refpurpose>
 </refnamediv>

 <indexterm zone="sql-start-transaction">
  <primary>START TRANSACTION</primary>
 </indexterm>

 <refsynopsisdiv>
<synopsis>
START TRANSACTION [ <replaceable class="parameter">transaction_mode</replaceable> [, ...] ]

where <replaceable class="parameter">transaction_mode</replaceable> is one of:

    ISOLATION LEVEL { SERIALIZABLE | REPEATABLE READ | READ COMMITTED | READ UNCOMMITTED }
    READ WRITE | READ ONLY
</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   This command begins a new transaction block. If the isolation level or
   read/write mode is specified, the new transaction has those
   characteristics, as if <xref linkend="sql-set-transaction"
   endterm="sql-set-transaction-title"> was executed. This is the same
   as the <xref linkend="sql-begin" endterm="sql-begin-title"> command.
  </para>
 </refsect1>

 <refsect1>
  <title>Parameters</title>

  <para>
   Refer to <xref linkend="sql-set-transaction"
   endterm="sql-set-transaction-title"> for information on the meaning
   of the parameters to this statement.
  </para>
 </refsect1>

 <refsect1>
  <title>Compatibility</title>

  <para>
   In the standard, it is not necessary to issue <command>START TRANSACTION</>
   to start a transaction block: any SQL command implicitly begins a block.
   <productname>PostgreSQL</productname>'s behavior can be seen as implicitly
   issuing a <command>COMMIT</command> after each command that does not
   follow <command>START TRANSACTION</> (or <command>BEGIN</command>),
   and it is therefore often called <quote>autocommit</>.
   Other relational database systems may offer an autocommit feature
   as a convenience.
  </para>

  <para>
   The SQL standard requires commas between successive <replaceable
   class="parameter">transaction_modes</replaceable>, but for historical
   reasons <productname>PostgreSQL</productname> allows the commas to be
   omitted.
  </para>

  <para>
   See also the compatibility section of <xref linkend="sql-set-transaction"
   endterm="sql-set-transaction-title">.
  </para>
 </refsect1>

 <refsect1>
  <title>See Also</title>

  <simplelist type="inline">
   <member><xref linkend="sql-begin" endterm="sql-begin-title"></member>
   <member><xref linkend="sql-commit" endterm="sql-commit-title"></member>
   <member><xref linkend="sql-rollback" endterm="sql-rollback-title"></member>
   <member><xref linkend="sql-savepoint" endterm="sql-savepoint-title"></member>
   <member><xref linkend="sql-set-transaction" endterm="sql-set-transaction-title"></member>
  </simplelist>
 </refsect1>
</refentry>

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