<!--

$Header: /cvsroot/pgsql/doc/src/sgml/ref/abort.sgml,v 1.4 1999/07/22 15:09:05 thomas Exp $

Postgres documentation

-->

<refentry id="SQL-ABORT">

<refmeta>

<refentrytitle>

<refentrytitle id="sql-abort-title">

ABORT

</refentrytitle>

<refmiscinfo>SQL - Language Statements</refmiscinfo>

</refnamediv>

<refsynopsisdiv>

<refsynopsisdivinfo>

<date>1998-09-27</date>

<date>1999-07-20</date>

</refsynopsisdivinfo>

<synopsis>

ABORT [TRANSACTION |WORK ]

ABORT [WORK |TRANSACTION ]

</synopsis>

<refsect2 id="R2-SQL-ABORT-1">

<!-- allfiles.sgml

- -->

<!--

-->

<!entity intro-ref system "intro-ref.sgml">

<!entity commands system "commands.sgml">

<!entity trim system "trim.sgml">

<!entity upper system "upper.sgml">

<!-- these are folded into create_table.sgml

<!entity check system "check.sgml">

<!entity constraints system "constraint.sgml">

<!entity default system "default.sgml">

<!entity notNull system "not_null.sgml">

<!entity primaryKey system "primary_key.sgml">

<!entity unique system "unique.sgml">

-->

<!-- these are folded into select.sgml

<!entity groupBy system "group_by.sgml">

<!entity having system "having.sgml">

<!entity orderBy system "order_by.sgml">

<!entity union system "union.sgml">

-->

<!-- these are in the "commands" reference chapter -->

<!entity abort system "abort.sgml">

<!entity alterTable system "alter_table.sgml">

<!entity dropType system "drop_type.sgml">

<!entity dropUser system "drop_user.sgml">

<!entity dropView system "drop_view.sgml">

<!entity end system "end.sgml">

<!entity explain system "explain.sgml">

<!entity fetch system "fetch.sgml">

<!entity grant system "grant.sgml">

<!entity createuser system "createuser.sgml">

<!entity destroydb system "destroydb.sgml">

<!entity destroyuser system "destroyuser.sgml">

<!entity ecpgRef system "ecpg-ref.sgml">

<!entity initdb system "initdb.sgml">

<!entity initlocation system "initlocation.sgml">

<!entity ipcclean system "ipcclean.sgml">

<!entity pgAccess system "pgaccess-ref.sgml">

<!entity pgAdmin system "pgadmin-ref.sgml">

<!entity pgDump system "pg_dump.sgml">

<!entity pgDumpall system "pg_dumpall.sgml">

<!entity pgPasswd system "pg_passwd.sgml">

<!entity pgUpgrade system "pg_upgrade.sgml">

<!entity postgres system "postgres-ref.sgml">

<!entity postmaster system "postmaster.sgml">

<!--

$Header: /cvsroot/pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.8 1999/07/22 15:09:06 thomas Exp $

Postgres documentation

-->

<refentry id="SQL-ALTERTABLE">

<refmeta>

<refentrytitle>

<refentrytitle id="sql-altertable-title">

ALTER TABLE

</refentrytitle>

<refmiscinfo>SQL - Language Statements</refmiscinfo>

</refnamediv>

<refsynopsisdiv>

<refsynopsisdivinfo>

<date>1998-04-15</date>

<date>1999-07-20</date>

</refsynopsisdivinfo>

<synopsis>

ALTER TABLE <replaceable class="PARAMETER">table</replaceable>

</para>

<para>

<quote>[*]</quote> following a name of a table indicates that statement

<quote>*</quote> following a name of a table indicates that the statement

should be run over that table and all tables below it in the

inheritance hierarchy.

inheritance hierarchy;

by default, the attribute will not be added to or renamed in any of the subclasses.

This should always be done when adding or modifying an attribute in a

superclass. If it is not, queries on the inheritance hierarchy

such as

<programlisting>

SELECT <replaceable>NewColumn</replaceable> FROM <replaceable>SuperClass</replaceable>*

</programlisting>

will not work because the subclasses will be missing an attribute

found in the superclass.

</para>

<para>

For efficiency reasons, default values for added attributes are

not placed in existing instances of a class.

That is, existing instances will have NULL values in the new

attributes. If non-NULL values are desired, a subsequent

<command>UPDATE</command> query

(<xref linkend="sql-update-title" endterm="sql-update-title">)

should be run.

</para>

<para>

You must own the class in order to change its schema.

Renaming any part of the schema of a system

catalog is not permitted.

The <citetitle>PostgreSQL User's Guide</citetitle> has further

information on inheritance.

</para>

<!--

$Header: /cvsroot/pgsql/doc/src/sgml/ref/alter_user.sgml,v 1.8 1999/07/22 15:09:06 thomas Exp $

Postgres documentation

-->

<refentry id="SQL-ALTERUSER">

<refmeta>

<refentrytitle>

<refentrytitle id="sql-alteruser-title">

ALTER USER

</refentrytitle>

<refmiscinfo>SQL - Language Statements</refmiscinfo>

</refnamediv>

<refsynopsisdiv>

<refsynopsisdivinfo>

<date>1998-09-08</date>

<date>1999-07-20</date>

</refsynopsisdivinfo>

<synopsis>

ALTER USER <replaceable class="PARAMETER">username</replaceable> [ WITH PASSWORD <replaceable class="PARAMETER">password</replaceable> ]

<command>ALTER USER</command> is used to change the attributes of a user's

<productname>Postgres</productname> account.

Please note that it is not possible

to alter a user's "usesysid" via the alter user

to alter a user's "<literal>usesysid</literal>" via the alter user

statement. Also, it is only possible for the

<productname>Postgres</productname>

user or any user with read and modify permissions on

<para>

If any of the clauses of the alter user statement are

omitted, the corresponding value in the"pg_shadow" table

omitted, the corresponding value in the<literal>pg_shadow</literal> table

is left unchanged.

</para>

<title>

Compatibility

</title>

<para>

</para>

<refsect2 id="R2-SQL-ALTERUSER-4">

<refsect2info>

<refentry id="SQL-BEGINWORK">

<!--

$Header: /cvsroot/pgsql/doc/src/sgml/ref/begin.sgml,v 1.9 1999/07/22 15:09:06 thomas Exp $

Postgres documentation

-->

<refentry id="SQL-BEGIN">

<refmeta>

<refentrytitle id="SQL-BEGINWORK-TITLE">

<refentrytitle id="SQL-BEGIN-TITLE">

BEGIN

</refentrytitle>

<refmiscinfo>SQL - Language Statements</refmiscinfo>

</refnamediv>

<refsynopsisdiv>

<refsynopsisdivinfo>

<date>1999-06-11</date>

<date>1999-07-20</date>

</refsynopsisdivinfo>

<synopsis>

BEGIN [ WORK | TRANSACTION ]

</synopsis>

<refsect2 id="R2-SQL-BEGINWORK-1">

<refsect2 id="R2-SQL-BEGIN-1">

<refsect2info>

<date>1999-06-11</date>

</refsect2info>

<title>

Inputs

</title>

<para>

None.

<variablelist>

<varlistentry>

<term>WORK</term>

<term>TRANSACTION</term>

<listitem>

<para>

Optional keywords. They have no effect.

</para>

</listitem>

</varlistentry>

</variablelist>

</para>

</refsect2>

<refsect2 id="R2-SQL-BEGINWORK-2">

<refsect2 id="R2-SQL-BEGIN-2">

<refsect2info>

<date>1999-06-11</date>

</refsect2info>

</refsect2>

</refsynopsisdiv>

<refsect1 id="R1-SQL-BEGINWORK-1">

<refsect1 id="R1-SQL-BEGIN-1">

<refsect1info>

<date>1999-06-11</date>

</refsect1info>

(if execution was successful, otherwise a rollback is done).

<command>BEGIN</command> initiates a user transaction in chained mode,

i.e. all user statements after <command>BEGIN</command> command will

be executed in a single transaction until an explicit COMMIT, ROLLBACK

be executed in a single transaction until an explicit

<xref linkend="sql-commit-title" endterm="sql-commit-title">,

<xref linkend="sql-rollback-title" endterm="sql-rollback-title">,

or execution abort. Statements in chained mode are executed much faster,

because transaction start/commit requires significant CPU and disk

activity. Execution of multiple statements inside a transaction

is READ COMMITTED, where queries inside the transaction see only changes

committed before query execution. So, you have to use

<command>SET TRANSACTION ISOLATION LEVEL SERIALIZABLE</command>

just after BEGIN if you need more rigorous transaction isolation.

just after<command>BEGIN</command> if you need more rigorous transaction isolation.

In SERIALIZABLE mode queries will see only changes committed before

the entire

transaction began (actually, before execution of the first DML statement

(atomic, consistent, isolatable, and durable) property.

</para>

<refsect2 id="R2-SQL-BEGINWORK-3">

<refsect2 id="R2-SQL-BEGIN-3">

<refsect2info>

<date>1999-06-11</date>

</refsect2info>

</para>

<para>

Refer to the <command>LOCK</command> statement for further information

Refer to <xref linkend="sql-lock-title" endterm="sql-lock-title">

for further information

about locking tables inside a transaction.

</para>

</refsect2>

</refsect1>

<refsect1 id="R1-SQL-BEGINWORK-2">

<refsect1 id="R1-SQL-BEGIN-2">

<title>

Usage

</title>

</para>

</refsect1>

<refsect1 id="R1-SQL-BEGINWORK-3">

<refsect1 id="R1-SQL-BEGIN-3">

<title>

Compatibility

</title>

<para>

<command>BEGIN</command>

is a <productname>Postgres</productname> language extension.

</para>

<refsect2 id="R2-SQL-BEGINWORK-4">

<refsect2 id="R2-SQL-BEGIN-4">

<refsect2info>

<date>1999-06-11</date>

</refsect2info>

<title>

SQL92

</title>

<para>

There is no explicit BEGIN WORK command in <acronym>SQL92</acronym>;

<para>

<command>BEGIN</command>

is a <productname>Postgres</productname> language extension.

There is no explicit <command>BEGIN</command>

command in <acronym>SQL92</acronym>;

transaction initiation is always implicit and it terminates either

with a COMMIT orwith aROLLBACK statement.

with a<command>COMMIT</command> or<command>ROLLBACK</command> statement.

<note>

<para>

<!--

$Header: /cvsroot/pgsql/doc/src/sgml/ref/close.sgml,v 1.7 1999/07/22 15:09:06 thomas Exp $

Postgres documentation

-->

<refentry id="SQL-CLOSE">

<refmeta>

<refentrytitle>

<refentrytitle id="SQL-CLOSE-TITLE">

CLOSE

</refentrytitle>

<refmiscinfo>SQL - Language Statements</refmiscinfo>

</refnamediv>

<refsynopsisdiv>

<refsynopsisdivinfo>

<date>1998-09-08</date>

<date>1999-07-20</date>

</refsynopsisdivinfo>

<synopsis>

CLOSE <replaceable class="PARAMETER">cursor</replaceable>

<title>

Compatibility

</title>

<para>

</para>

<refsect2 id="R2-SQL-CLOSE-4">

<refsect2info>