DBSchema(3)

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 a different process. You can write SQL CREATE statements statements for different databases from a single source. In recent versions, you can transform one schema to another, adding any necessary new columsn and tables.

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 the quoting and type mapping will be more reliable.

    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 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.

     #Optionally, 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 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.

    Right now this method knows how to add new tables and alter existing tables. It doesn't know how to drop tables yet.

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

update_schema 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
    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.

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

COPYRIGHT
Copyright (c) 2000-2006 Ivan Kohler Copyright (c) 2000 Mail Abuse Prevention System LLC All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

BUGS
Indices are not stored by name. Index representation could use an overhaul.

Multiple primary keys are not yet supported.

Foreign keys and other constraints are not yet supported.

Eventually it would be nice to have additional transformations (deleted, modified columns, added/modified/indices (probably need em named first), added/deleted tables

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).

pretty_print is actually pretty ugly.

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

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

sql_update_schema doesn't drop tables yet.

SEE ALSO
DBIx::DBSchema::Table, DBIx::DBSchema::ColGroup, DBIx::DBSchema::ColGroup::Unique, DBIx::DBSchema::ColGroup::Index, DBIx::DBSchema::Column, DBIx::DBSchema::DBD, DBIx::DBSchema::DBD::mysql, DBIx::DBSchema::DBD::Pg, FS::Record, DBI

POD ERRORS
Hey! The above document had some coding errors, which are explained below:

Around line 362:
    =cut found outside a pod block. Skipping to next block.