NAME

SHARYANTO::SQL::Schema - Routine and convention to create/update your application's DB schema

VERSION

version 0.07

DESCRIPTION

This module uses Log::Any for logging.

To use this module, you typically run the create_or_update_db_schema() routine at the start of your program/script, e.g.:

 use DBI;
 use SHARYANTO::SQL::Schema qw(create_or_update_db_schema);
 my $spec = {...}; # the schema specification
 my $dbh = DBI->connect(...);
 my $res = create_or_update_db_schema(dbh=>$dbh, spec=>$spec);
 die "Cannot run the application: cannot create/upgrade database schema: $res->[1]"
     unless $res->[0] == 200;

This way, your program automatically creates/updates database schema when run. Users need not know anything.

FAQ

Why the name SHARYANTO::*?

I haven't decided on a better name. See SHARYANTO.

How do I see each SQL statement as it is being executed?

Try using Log::Any::For::DBI, e.g.:

 % TRACE=1 perl -MLog::Any::For::DBI -MLog::Any::App yourapp.pl ...

SEE ALSO

Some other database migration tools that directly uses SQL:

• Database::Migrator

  Pretty much similar, albeit more fully-fledged/involved. You have to use OO style. You put each version's SQL in a separate file and subdirectory. Perl scripts can also be executed for each version upgrade. Meta table is configurable (default recommended is 'AppliedMigrations').

AUTHOR

Steven Haryanto <stevenharyanto@gmail.com>

COPYRIGHT AND LICENSE

This software is copyright (c) 2013 by Steven Haryanto.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

FUNCTIONS

None are exported by default, but they are exportable.

create_or_update_db_schema(%args) -> [status, msg, result, meta]

Routine and convention to create/update your application's DB schema.

With this routine (and some convention) you can easily create and update database schema for your application in a simple (and boring a.k.a. using plain SQL) way.

Version: version is an integer and starts from 1. Each software release with schema change will bump the version number to 1. Version information is stored in a special table called meta (SELECT value FROM meta WHERE name='schema_version').

You supply the SQL statements in spec. spec is a hash which contains the key install (the value of which is a series of SQL statements to create the schema from nothing). It should be the SQL statements to create the latest version of the schema.

There should also be zero or more upgrade_to_v$VERSION keys, the value of each is a series of SQL statements to upgrade from ($VERSION-1) to $VERSION. So there could be upgrade_to_v2, upgrade_to_v3, and so on up the latest version.

This routine will connect to database and check the current schema version. If meta table does not exist yet, the SQL statements in install will be executed. The meta table will also be created and a row ('schema_version', 1) is added.

If meta table already exists, schema version will be read from it and one or more series of SQL statements from upgrade_to_v$VERSION will be executed to bring the schema to the latest version.

Currently only tested on MySQL, Postgres, and SQLite. Postgres is recommended because it can do transactional DDL (a failed upgrade in the middle will not cause the database schema state to be inconsistent, e.g. in-between two versions).

Arguments ('*' denotes required arguments):

• dbh* => obj

  DBI database handle.

• spec* => hash

  SQL statements to create and update schema.

  Example:

      {
          install => [
              'CREATE TABLE IF NOT EXISTS t1 (...)',
              'CREATE TABLE IF NOT EXISTS t2 (...)',
          ],
      
          upgrade_to_v2 => [
              'ALTER TABLE t1 ADD COLUMN c5 INT NOT NULL',
              'CREATE UNIQUE INDEX i1 ON t2(c1)',
          ],
      
          upgrade_to_v3 => [
              'ALTER TABLE t2 DROP COLUMN c2',
          ],
      }

Return value:

Returns an enveloped result (an array). First element (status) is an integer containing HTTP status code (200 means OK, 4xx caller error, 5xx function error). Second element (msg) is a string containing error message, or 'OK' if status is 200. Third element (result) is optional, the actual result. Fourth element (meta) is called result metadata and is optional, a hash that contains extra information.

cpanm SHARYANTO::SQL::Schema

perl -MCPAN -e shell
install SHARYANTO::SQL::Schema