How to generate SQL statements from Sequel migrations

Question

I would like to output the generated SQL statements from Sequel migrations to a file without having a connection to the actual database. I need this because I want to export the statements in MySQL form, but I use PostgreSQL normally.

I could try to set up MySQL and output with the -E option while creating the database, but that is not how things should work right?

What I need is something like:

sequel -m db/migrations/ -E --type mysql > msysql_statements.sql

I'm using Sequel with migrations.

Is there a way to achieve this?

Trials according to answers

I tried the command proposed Jeremy Evans'es answer:

sequel -m db/migrations/ -t -E mock://mysql

the error is following output:

  I, [2016-07-18T13:57:09.020630 #21573]  INFO -- : SELECT NULL AS `nil` FROM `schema_migrations` LIMIT 1
  I, [2016-07-18T13:57:09.020802 #21573]  INFO -- : SELECT * FROM `schema_migrations` LIMIT 1
  /home/me/.rvm/gems/ruby-2.2.1/gems/sequel-4.34.0/lib/sequel/extensions/migration.rb:751:in `schema_dataset': Migrator table schema_migrations does not contain column filename (Sequel::Migrator::Error)
    from /home/me/.rvm/gems/ruby-2.2.1/gems/sequel-4.34.0/lib/sequel/extensions/migration.rb:450:in `initialize'
    from /home/me/.rvm/gems/ruby-2.2.1/gems/sequel-4.34.0/lib/sequel/extensions/migration.rb:652:in `initialize'
    from /home/me/.rvm/gems/ruby-2.2.1/gems/sequel-4.34.0/lib/sequel/extensions/migration.rb:397:in `new'
    from /home/me/.rvm/gems/ruby-2.2.1/gems/sequel-4.34.0/lib/sequel/extensions/migration.rb:397:in `run'
    from /home/me/.rvm/gems/ruby-2.2.1/gems/sequel-4.34.0/lib/sequel/extensions/migration.rb:368:in `apply'
    from /home/me/.rvm/gems/ruby-2.2.1/gems/sequel-4.34.0/bin/sequel:160:in `<top (required)>'
    from /home/me/.rvm/gems/ruby-2.2.1/bin/sequel:23:in `load'
    from /home/me/.rvm/gems/ruby-2.2.1/bin/sequel:23:in `<main>'
    from /home/me/.rvm/gems/ruby-2.2.1/bin/ruby_executable_hooks:15:in `eval'
    from /home/me/.rvm/gems/ruby-2.2.1/bin/ruby_executable_hooks:15:in `<main>'

Unfortunately it seems to try to access something from the mock-database.

Update

With Jeremy's answer i had something to work with, i came up with following hacky workaround, which generates at least most of the statements, but not all :( :

• issue sequel -m db/migrations/ -t -E mock://mysql > mysql-statements.sql
• if you get an exeption, comment out raise statement in sequel code
• at the and you will have an output with the correct sql statement, but with extra logging information
• remove that extra information by using some replacement tool or easier with multi-cursor-editors like sublime or atom
• put semicolons at the end of the lines
• now you have correct mysql statements
• Dont forget to revert modifications on sequel-gem-code ;)

Answer 1

Nulldb https://github.com/nulldb/nulldb will be perfect for this.

Answer 2

There is no way to do it in bash like you want to, but you can use tools for that. Dump your PostgreSQL into this tool and it should create a MySQL from it.

There is another tool with various DB frameworks for your choosing - SQLines

Answer 3

sequel -m db/migrations/ -E mock://mysql > msysql_statements.sql