NAME
    Oracle::Trigger - Perl class for creating Oracle triggers

SYNOPSIS
      use Oracle::Trigger;

      my %cfg = ('conn_string'=>'usr/pwd@db', 'table_name'=>'my_ora_tab');
      my $ot = Oracle::Trigger->new;
      # or combine the two together
      my $ot = Oracle::Trigger->new(%cfg);
      my $sql= $ot->prepare(%cfg); 
      $ot->execute();    # actually create the audit table and trigger

      # call the methods directly
      my $sql = $ot->create_data_trigger($tn,$cns,$dbh,$trg,$aud); 
      my $ar  = $ot->create_data_audit($tn,$cns,$dbh,$aud,$drp); 

DESCRIPTION
    This class contains methods to create audit tables and triggers for
    Oracle tables.

  new (conn_string=>'usr/pwd@db',table_name=>'my_table')

    Input variables:

      $cs  - Oracle connection string in usr/pwd@db
      $tn  - Oracle table name without schema

    Variables used or routines called:

      None

    How to use:

       my $obj = new Oracle::Trigger;      # or
       my $obj = Oracle::Trigger->new;     # or
       my $cs  = 'usr/pwd@db';
       my $tn  = 'my_table'; 
       my $obj = Oracle::Trigger->new(cs=>$cs,tn=>$tn); # or
       my $obj = Oracle::Trigger->new('cs',$cs, 'tn',$tn); 

    Return: new empty or initialized Oracle::Trigger object.

    This method constructs a Perl object and capture any parameters if
    specified. It creates and defaults the following variables:

      $self->{conn_string} = "";       # or $self->{cs}
      $self->{table_name}  = "";       # or $self->{tn}  

METHODS
    The following are the common methods, routines, and functions defined in
    this class.

  Exported Tag: All

    The *:all* tag includes all the methods or sub-rountines defined in this
    class.

      use Oracle::Trigger qw(:all);

    It includes the following sub-routines:

   prepare($cs, $tn, $tp)

    Input variables:

      $cs  - Oracle connection string in usr/pwd@db
      $tn  - Oracle table name without schema
      $tp  - trigger type
             DATA - trigger to audit a table. This is the default.

    Variables used or routines called:

      Debug::EchoMessage
        echoMSG - display message
      {cs} - connection string
      {tn} - table name 
      {drop_audit}   - whether to drop audit table if it exists
      {audit_table}  - audit table name, default to aud${$tn}
      {trigger_name} - trigger name, default to trg${$tn}

    How to use:

      my $ar = $self->prepare('usr/pwd@db','my_tab');

    Return: $hr - a hash array ref containing the following keys:

      dbh         - the database handler
      sql_audit   - SQL statement for creating the audit table
      sql_trigger - SQL statement for creating the trigger

    This method performs the following tasks:

      1) create a database handler
      2) check the existance of the table 
      3) generate script for creating audit table
      4) generate script for creating trigger

    And it sets the following internal variable as well:

      {dbh} - database handler
      {sql_audit} - sql statements to create audit table
      {sql_trigger} - sql statement to create trigger

   execute($typ)

    Input variables:

      $typ - action type:
             TRIGGER - create trigger only 
             AUDIT   - create audit table only
             default - null and will create both

    Variables used or routines called:

      {dbh} - database handler
      {sql_audit} - sql statements to create audit table
      {sql_trigger} - sql statement to create trigger

    How to use:

      my $status = $self->execute();
      $self->execute();

    Return: 0|1: 0 - OK; 1 - failed

    This method submits the sql statement to Oracle server to create audit
    table or trigger or both. The default is to create both. If the audit
    table exists, it will skip creating the audit table. You either need to
    manually drop the table or set {drop_audit} to '1' before you run
    prepare().

   create_data_trigger($tn, $cns, $dbh, $trg, $aud)

    Input variables:

      $tn  - Oracle table name without schema
      $cns - a list of column names separated by comma
      $dbh - database handler
      $trg - trigger name defaults to "TRG${$tn}"
      $aud - audit table name defaults to "AUD${$tn}"

    Variables used or routines called:

    How to use:

      my $tn = 'mytab'; 
      my $tg = 'mytab_trg';
      my $cns = 'id,name';
      my $dbh = $self->get_dbh('usr/pwd@db'); 
      # No DB connection: $tn,$cns and default trigger name to trg${$tn}:
      my $sql = $self->create_data_trigger($tn,$cns); 
      # Need DB connection: $tn,$dbh
      $sql = $self->create_data_trigger($tn,'',$dbh,$tg);  
      # table does not exist, $cns will be used; if table exists, then
      # $cns will be checked agaign column names from table
      $sql = $self->create_data_trigger($tn,$cns,$dbh);  

    Return: $sql - SQL statement to create a DATA trigger.

    This method performs the following tasks:

      1) check inputs, table name is required
      2) check the existance of the table. 
      3) compose columns
      4) compose SQL code for creating trigger

    An empty string will be returned if the inputs do not meet one of the
    following cases: a) table name and column list are provided; b) table
    name and database handler are provided so that column names are obtained
    from the table; c) table name, column list, and database handler are
    provided, then column names are obtained from the table and compared
    with the column list are well. None existing columns in the column list
    will be excluded from trigger.

   create_data_audit($tn, cnsp, $dbh, $aud, $drp)

    Input variables:

      $tn  - source table name without schema
      $cns - column names separated by comma
      $dbh - database handler
      $aud - audit table name
      $drp - whether to drop audit table before creating it
             default is 0 (no)

    Variables used or routines called:

    How to use:

      my $tn  = 'mytab'; 
      my $aud = 'aud$mytab';
      my $dbh = $self->get_dbh('usr/pwd@db');
      # create audit table 
      # and default audit name is aud${$tn}:
      my $ar = $self->create_data_audit($tn,$cns); 

      # give a trigger name
      $sql = $self->create_data_audit($tn,$tg);  
      # table does not exist, but colun names are provided:
      $sql = $self->create_data_audit($tn,'','id,name');  
      # if $dbh is provided, the table existence will be checked
      $sql = $self->create_data_audit($tn,'','',$dbh);

    Return: $ar - array ref containing SQL statements for dropping and
    creating audit table.

    This method performs the following tasks:

      1) check inputs, table name is required
      2) check the existance of the table. 
      3) compose columns
      4) compose SQL code for creating trigger

    An empty string will be returned if the inputs do not meet one of the
    following cases: a) table name and column list are provided; b) table
    name and database handler are provided so that column names are obtained
    from the table; c) table name, column list, and database handler are
    provided, then column names are obtained from the table and compared
    with the column list are well. None existing columns in the column list
    will be excluded from trigger.

HISTORY
    * Version 0.1
        This version is to test the procedures and create DATA trigger.

        04/22/2005 (htu) - finished creating DATA trigger rountines.

    * Version 0.2
        04/29/2005 (htu) - modified some descriptions and moved the common
        routines to Oracle::DML::Common.

    * Version 0.21
        Since get_table_definition is moved to Oracle::Schema, we change it
        here to use Oracle::Schema.

    * Version 0.22
        Re-wrote *prepare* method so that it can prepare SQL statments based
        on trigger type.

        Added *create_data_trigger* and *create_data_audit* methods.

SEE ALSO (some of docs that I check often)
        Data::Describe, Oracle::Loader, CGI::Getopt, File::Xcopy,
        perltoot(1), perlobj(1), perlbot(1), perlsub(1), perldata(1),
        perlsub(1), perlmod(1), perlmodlib(1), perlref(1), perlreftut(1).

AUTHOR
        Copyright (c) 2005 Hanming Tu. All rights reserved.

        This package is free software and is provided "as is" without
        express or implied warranty. It may be used, redistributed and/or
        modified under the terms of the Perl Artistic License (see
        http://www.perl.com/perl/misc/Artistic.html)