Ubuntu Manpage: DBIx::DBSchema - Database-independent schema objects

Provided by: libdbix-dbschema-perl_0.44-1_all

NAME

       DBIx::DBSchema - Database-independent schema objects

SYNOPSIS

         use DBIx::DBSchema;

         $schema = new DBIx::DBSchema @dbix_dbschema_table_objects;
         $schema = new_odbc DBIx::DBSchema $dbh;
         $schema = new_odbc DBIx::DBSchema $dsn, $user, $pass;
         $schema = new_native DBIx::DBSchema $dbh;
         $schema = new_native DBIx::DBSchema $dsn, $user, $pass;

         $schema->save("filename");
         $schema = load DBIx::DBSchema "filename" or die $DBIx::DBSchema::errstr;

         $schema->addtable($dbix_dbschema_table_object);

         @table_names = $schema->tables;

         $DBIx_DBSchema_table_object = $schema->table("table_name");

         @sql = $schema->sql($dbh);
         @sql = $schema->sql($dsn, $username, $password);
         @sql = $schema->sql($dsn); #doesn't connect to database - less reliable

         $perl_code = $schema->pretty_print;
         %hash = eval $perl_code;
         use DBI qw(:sql_types); $schema = pretty_read DBIx::DBSchema \%hash;

DESCRIPTION

       DBIx::DBSchema objects are collections of DBIx::DBSchema::Table objects and represent a
       database schema.

       This module implements an OO-interface to database schemas.  Using this module, you can
       create a database schema with an OO Perl interface.  You can read the schema from an
       existing database.  You can save the schema to disk and restore it in a different process.
       You can write SQL CREATE statements statements for different databases from a single
       source.  You can transform one schema to another, adding any necessary new columns,
       tables, indices and foreign keys.

       Currently supported databases are MySQL, PostgreSQL and SQLite.  Sybase and Oracle drivers
       are partially implemented.  DBIx::DBSchema will attempt to use generic SQL syntax for
       other databases.  Assistance adding support for other databases is welcomed.  See
       DBIx::DBSchema::DBD, "Driver Writer's Guide and Base Class".

METHODS

new TABLE_OBJECT, TABLE_OBJECT, ...
Creates a new DBIx::DBSchema object.

new_odbc DATABASE_HANDLE | DATA_SOURCE USERNAME PASSWORD [ ATTR ]
Creates a new DBIx::DBSchema object from an existing data source, which can be
specified by passing an open DBI database handle, or by passing the DBI data source
name, username, and password. This uses the experimental DBI type_info method to
create a schema with standard (ODBC) SQL column types that most closely correspond to
any non-portable column types. Use this to import a schema that you wish to use with
many different database engines. Although primary key and (unique) index information
will only be read from databases with DBIx::DBSchema::DBD drivers (currently MySQL and
PostgreSQL), import of column names and attributes *should* work for any database.
Note that this method only uses "ODBC" column types; it does not require or use an
ODBC driver.

new_native DATABASE_HANDLE | DATA_SOURCE USERNAME PASSWORD [ ATTR ]
Creates a new DBIx::DBSchema object from an existing data source, which can be
specified by passing an open DBI database handle, or by passing the DBI data source
name, username and password. This uses database-native methods to read the schema,
and will preserve any non-portable column types. The method is only available if
there is a DBIx::DBSchema::DBD for the corresponding database engine (currently, MySQL
and PostgreSQL).

load FILENAME
Loads a DBIx::DBSchema object from a file. If there is an error, returns false and
puts an error message in $DBIx::DBSchema::errstr;

save FILENAME
Saves a DBIx::DBSchema object to a file.

addtable TABLE_OBJECT
Adds the given DBIx::DBSchema::Table object to this DBIx::DBSchema.

tables
Returns a list of the names of all tables.

table TABLENAME
Returns the specified DBIx::DBSchema::Table object.

sql [ DATABASE_HANDLE | DATA_SOURCE [ USERNAME PASSWORD [ ATTR ] ] ]
Returns a list of SQL `CREATE' statements for this schema.

The data source can be specified by passing an open DBI database handle, or by passing
the DBI data source name, username and password.

Although the username and password are optional, it is best to call this method with a
database handle or data source including a valid username and password - a DBI
connection will be opened and used to check the database version as well as for more
reliable quoting and type mapping. Note that the database connection will be used
passively, not to actually run the CREATE statements.

If passed a DBI data source (or handle) such as `DBI:mysql:database' or
`DBI:Pg:dbname=database', will use syntax specific to that database engine. Currently
supported databases are MySQL and PostgreSQL.

If not passed a data source (or handle), or if there is no driver for the specified
database, will attempt to use generic SQL syntax.

sql_update_schema [ OPTIONS_HASHREF, ] PROTOTYPE_SCHEMA [ DATABASE_HANDLE | DATA_SOURCE [
USERNAME PASSWORD [ ATTR ] ] ]
Returns a list of SQL statements to update this schema so that it is idential to the
provided prototype schema, also a DBIx::DBSchema object.

Right now this method knows how to add new tables and alter existing tables, including
indices. If specifically requested by passing an options hashref with drop_tables set
true before all other arguments, it will also drop tables.

See "sql_alter_table" in DBIx::DBSchema::Table, "sql_add_column" in
DBIx::DBSchema::Column and "sql_alter_column" in DBIx::DBSchema::Column for additional
specifics and limitations.

The data source can be specified by passing an open DBI database handle, or by passing
the DBI data source name, username and password.

If not passed a data source (or handle), or if there is no driver for the specified
database, will attempt to use generic SQL syntax.

update_schema [ OPTIONS_HASHREF, ] PROTOTYPE_SCHEMA, DATABASE_HANDLE | DATA_SOURCE [
USERNAME PASSWORD [ ATTR ] ]
Same as sql_update_schema, except actually runs the SQL commands to update the schema.
Throws a fatal error if any statement fails.

pretty_print
Returns the data in this schema as Perl source, suitable for assigning to a hash.

pretty_read HASHREF
This method is not recommended. If you need to load and save your schema to a file,
see the "load" and "save" methods.

Creates a schema as specified by a data structure such as that created by pretty_print
method.

AUTHORS

       Ivan Kohler <ivan-dbix-dbschema@420.am>

       Charles Shapiro <charles.shapiro@numethods.com> and Mitchell Friedman
       <mitchell.friedman@numethods.com> contributed the start of a Sybase driver.

       Daniel Hanks <hanksdc@about-inc.com> contributed the Oracle driver.

       Jesse Vincent contributed the SQLite driver and fixes to quiet down internal usage of the
       old API.

       Slaven Rezic <srezic@cpan.org> contributed column and table dropping, Pg bugfixes and
       more.

CONTRIBUTIONS

       Contributions are welcome!  I'm especially keen on any interest in the top items/projects
       below under BUGS.

COPYRIGHT

       Copyright (c) 2000-2007 Ivan Kohler Copyright (c) 2000 Mail Abuse Prevention System LLC
       Copyright (c) 2007-2013 Freeside Internet Services, Inc.  All rights reserved.  This
       program is free software; you can redistribute it and/or modify it under the same terms as
       Perl itself.

BUGS AND TODO

       Multiple primary keys are not yet supported.

       Foreign keys: need to support dropping, NOT VALID, reverse engineering w/mysql

       Need to port and test with additional databases

       Each DBIx::DBSchema object should have a name which corresponds to its name within the SQL
       database engine (DBI data source).

       Need to support "using" index attribute in pretty_read and in reverse engineering

       sql CREATE TABLE output should convert integers (i.e. use DBI qw(:sql_types);) to local
       types using DBI->type_info plus a hash to fudge things

   PRETTY_ BUGS
       pretty_print is actually pretty ugly.

       pretty_print isn't so good about quoting values...  save/load is a much better alternative
       to using pretty_print/pretty_read

       pretty_read is pretty ugly too.

       pretty_read should *not* create and pass in old-style unique/index indices when nothing is
       given in the read.

       Perhaps pretty_read should eval column types so that we can use DBI qw(:sql_types) here
       instead of externally.

       perhaps we should just get rid of pretty_read entirely.  pretty_print is useful for
       debugging, but pretty_read is pretty bunk.