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<?xml version="1.0" encoding="ISO-8859-1"?>
<!--
-
- This file is part of the OpenLink Software Virtuoso Open-Source (VOS)
- project.
-
- Copyright (C) 1998-2018 OpenLink Software
-
- This project is free software; you can redistribute it and/or modify it
- under the terms of the GNU General Public License as published by the
- Free Software Foundation; only version 2 of the License, dated June 1991.
-
- This program is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- General Public License for more details.
-
- You should have received a copy of the GNU General Public License along
- with this program; if not, write to the Free Software Foundation, Inc.,
- 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
-
-
-->
<refentry id="fn_signal">
<refmeta>
<refentrytitle>signal</refentrytitle>
<refmiscinfo>sql</refmiscinfo>
</refmeta>
<refnamediv>
<refname>signal</refname>
<refpurpose>Signal an exception in the calling procedure</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis id="fsyn_signal">
<funcprototype id="fproto_signal">
<funcdef><function>signal</function></funcdef>
<paramdef>in <parameter>sqlstate</parameter> varchar</paramdef>
<paramdef>in <parameter>message</parameter> varchar</paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 id="desc"><title>Description</title>
<para>This signals the given SQLSTATE with the message. The calling procedure will transfer control to the most appropriate local handler. In the absence of a local handler the procedure terminates and signals the exception in the scope where it was called from, until there either is a handler or there are no more calling procedures. If there is no handler in the entire stack of call contexts the error is signalled to the client.
Handlers can be declared with whenever .. goto and the declare handler for construct.
See the Virtuoso/PL documentation.
</para>
<screen>
CREATE PROCEDURE WITHDRAW (IN C_ID VARCHAR, IN DELTA NUMERIC)
{
DECLARE BAL NUMERIC;
DECLARE CR CURSOR FOR SELECT C_BALANCE FROM CUSTOMER WHERE C_ID = C_ID;
WHENEVER NOT FOUND GOTO NOCUSTOMER;
OPEN CR (EXCLUSIVE);
FETCH CR INTO BAL;
IF (BAL > DELTA)
UPDATE CUSTOMER SET C_BALANCE = BAL - DELTA WHERE CURRENT OF CR;
ELSE
SIGNAL ('NOMONEY', 'INSUFFICIENT BALANCE.');
RETURN;
NOCUSTOMER:
SIGNAL ('NOCUS', 'BAD CUSTOMER ID');
}
</screen>
</refsect1>
</refentry>
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