NAME

DBIx::Admin::TableInfo - A wrapper for table_info(), column_info(), *_key_info()

Synopsis

#!/usr/bin/perl

use strict;
use warnings;

use Data::Dumper;
use DBI;
use DBIx::Admin::TableInfo;

# ---------------------

my($dbh)    = DBI -> connect($ENV{'DBI_DSN'}, $ENV{'DBI_USER'}, $ENV{'DBI_PASS'});
my($schema) = $ENV{'DBI_DSN'} =~ /^dbi:Oracle/i ? uc $ENV{'DBI_USER'} : undef;

print Data::Dumper -> Dump
([
	DBIx::Admin::TableInfo -> new(dbh => $dbh, schema => $schema) -> info()
]);

Description

DBIx::Admin::TableInfo is a pure Perl module.

It is a convenient wrapper around these DBI methods:

table_info()
column_info()
primary_key_info()
foreign_key_info()

Warnings:

MySQL

The MySQL client DBD::mysql V 3.0002 does not support primary_key_info(), so this module emulates it by stockpiling a list of columns which have the attribute 'mysql_is_pri_key' set.

The problem with this is that if a primary key consists of more than 1 column, DBD::mysql does not indicate the order of these columns within the key, so this module pretends that they are in the same order as the order of columns returned by the call to column_info().

Likewise, DBD::mysql does not support foreign_key_info(), so in the case of MySQL, nothing is reported for foreign keys.

For MySQL V 5.0.18, section 14.2.6.4 of the manual says that for InnoDB tables, the SQL "show table status from 'db name' like 'table name'" will display the foreign key info in the column called 'Comment', but this is simply not true. The 'Comment' column contains a string such as 'InnoDB free: 4096 kB'.

Likewise, the SQL "show create table 'table name'" reveals than MySQL does not preserve 'create table' clauses such as 'references other_table(other_column)'.

So, at the moment, I see no way of displaying foreign key information under MySQL.

Oracle

Oracle table names matching /^BIN\$.+\$./ are ignored by this module.

Distributions

This module is available both as a Unix-style distro (*.tgz) and an ActiveState-style distro (*.ppd). The latter is shipped in a *.zip file.

See http://savage.net.au/Perl-modules.html for details.

See http://savage.net.au/Perl-modules/html/installing-a-module.html for help on unpacking and installing each type of distro.

Constructor and initialization

new(...) returns a DBIx::Admin::TableInfo object.

This is the class's contructor.

Usage: DBIx::Admin::TableInfo -> new().

This method takes a set of parameters. Only the dbh parameter is mandatory.

For each parameter you wish to use, call new as new(param_1 => value_1, ...).

catalog

This is the value passed in as the catalog parameter to table_info() and column_info().

The default value is undef.

undef was chosen because it given the best results with MySQL.

Note: The MySQL driver DBD::mysql V 2.9002 has a bug in it, in that it aborts if an empty string is used here, even though the DBI docs say an empty string can be used for the catalog parameter to table_info().

This parameter is optional.

dbh

This is a database handle.

This parameter is mandatory.

schema

This is the value passed in as the schema parameter to table_info() and column_info().

Note: If you are using Oracle, call new() with schema set to uc $user_name.

Note: If you are using Postgres, call new() with schema set to 'public'.

The default value is undef.

This parameter is optional.

table

This is the value passed in as the table parameter to table_info().

The default value is '%'.

This parameter is optional.

type

This is the value passed in as the type parameter to table_info().

The default value is 'TABLE'.

Note: If you are using Postgres, call new() with table set to 'table'.

This parameter is optional.

Method: columns($table_name, $by_position)

Returns an array ref of column names.

By default they are sorted by name.

However, if you pass in a true value for $by_position, they are sorted by the column attribute ORDINAL_POSITION.

Method: info()

Returns a hash ref of all available data.

The structure of this hash is described next:

First level: The keys are the names of the tables

my($info)       = $obj -> info();
my(@table_name) = sort keys %$info;

I use singular names for my arrays, hence @table_name rather than @table_names.

Second level: The keys are 'attributes', 'columns', 'foreign_keys' and 'primary_keys'

my($table_attributes) = $$info{$table_name}{'attributes'};

This is a hash ref of the table's attributes. The keys of this hash ref are determined by the database server.

my($columns) = $$info{$table_name}{'columns'};

This is a hash ref of the table's columns. The keys of this hash ref are the names of the columns.

my($foreign_keys) = $$info{$table_name}{'foreign_keys'};

This is a hash ref of the table's foreign keys. The keys of this hash ref are the names of the tables which contain foreign keys pointing to $table_name.

For MySQL, $foreign_keys will be the empty hash ref {}, as explained above.

my($primary_keys) = $$info{$table_name}{'primary_keys'};

This is a hash ref of the table's primary keys. The keys of this hash ref are the names of the columns which make up the primary key of $table_name.

For any database server, if there is more than 1 column in the primary key, they will be numbered (ordered) according to the hash key 'KEY_SEQ'.

For MySQL, if there is more than 1 column in the primary key, they will be artificially numbered according to the order in which they are returned by column_info(), as explained above.

Third level, after 'attributes': Table attributes

my($table_attributes) = $$info{$table_name}{'attributes'};

while ( ($name, $value) = each(%$table_attributes) )
{
	Use...
}

For the attributes of the tables, there are no more levels in the hash ref.

Third level, after 'columns': The keys are the names of the columns.

my($columns) = $$info{$table_name}{'columns'};

my(@column_name) = sort keys %$columns;

Fourth level: Column attributes

for $column_name (@column_name)
{
    while ( ($name, $value) = each(%{$columns{$column_name} }) )
    {
	    Use...
    }
}

Third level, after 'foreign_keys': The keys are the names of tables

These tables have foreign keys which point to the current table.

my($foreign_keys) = $$info{$table_name}{'foreign_keys'};

for $foreign_table (sort keys %$foreign_keys)
{
	$foreign_key = $$foreign_keys{$foreign_table};

	for $attribute (sort keys %$foreign_key)
	{
		Use...
	}
}

Third level, after 'primary_keys': The keys are the names of columns

These columns make up the primary key of the current table.

my($primary_keys) = $$info{$table_name}{'primary_keys'};

for $primary_key (sort{$$a{'KEY_SEQ'} <=> $$b{'KEY_SEQ'} } keys %$primary_keys)
{
	$primary = $$primary_keys{$primary_key};

	for $attribute (sort keys %$primary)
	{
		Use...
	}
}

Method: refresh()

Returns the same hash ref as info().

Use this after changing the database schema, when you want this module to re-interrogate the database server.

Method: tables()

Returns an array ref of table names.

They are sorted by name.

Warning: Oracle table names matching /^BIN\$.+\$./ are ignored by this module.

Example code

Here are tested parameter values for various database vendors:

MS Access

my($admin) = DBIx::Admin::TableInfo -> new(dbh => $dbh);

In other words, the default values for catalog, schema, table and type will Just Work.

MySQL

my($admin) = DBIx::Admin::TableInfo -> new(dbh => $dbh);

In other words, the default values for catalog, schema, table and type will Just Work.

Oracle

my($dbh)   = DBI -> connect($dsn, $username, $password);
my($admin) = DBIx::Admin::TableInfo -> new
(
	dbh    => $dbh,
	schema => uc $username, # Yep, upper case.
);

For Oracle, you probably want to ignore table names matching /^BIN\$.+\$./.

PostgreSQL

my($admin) = DBIx::Admin::TableInfo -> new
(
	dbh    => $dbh,
	schema => 'public',
	table  => 'table', # Yep, lower case.
);

For PostgreSQL, you probably want to ignore table names matching /^(pg_|sql_)/.

See the examples/ directory in the distro.

Tested Database Formats

I have used the program in the synopsis to read databases in these formats:

MS Access V 2: Yes, some businesses were still running V 2 as of July, 2004.
MS Access V 2002 and V 2003
MySQL V 4 and V 5
Oracle V 9.2.0
PostgreSQL V 7.3 and 8.1

I have written a set of modules - which are still being tested - under the DBIx::Admin::* namespace.

They will form the core of myadmin.cgi V 2. See http://savage.net.au/Perl-tutorials.html#tut_41

Changes

See Changes.txt.

Author

DBIx::Admin::TableInfo was written by Ron Savage <ron@savage.net.au> in 2004.

Home page: http://savage.net.au/index.html

Copyright

All Programs of mine are 'OSI Certified Open Source Software';
you can redistribute them and/or modify them under the terms of
The Artistic License, a copy of which is available at:
http://www.opensource.org/licenses/index.html

To install DBIx::Admin::TableInfo, copy and paste the appropriate command in to your terminal.

cpanm

cpanm DBIx::Admin::TableInfo

CPAN shell

perl -MCPAN -e shell
install DBIx::Admin::TableInfo

For more information on module installation, please visit the detailed CPAN module installation guide.

	Global
`s`	Focus search bar
`?`	Bring up this help dialog

	GitHub
`g` `p`	Go to pull requests
`g` `i`	go to github issues (only if github is preferred repository)

	POD
`g` `a`	Go to author
`g` `c`	Go to changes
`g` `i`	Go to issues
`g` `d`	Go to dist
`g` `r`	Go to repository/SCM
`g` `s`	Go to source
`g` `b`	Go to file browse

	Search terms
module: (e.g. module:Plugin)
distribution: (e.g. distribution:Dancer auth)
author: (e.g. author:SONGMU Redis)
version: (e.g. version:1.00)

NAME

Synopsis

Description

Distributions

Constructor and initialization

Method: columns($table_name, $by_position)

Method: info()

Method: refresh()

Method: tables()

Example code

Tested Database Formats

Related Modules

Changes

Author

Copyright

Module Install Instructions