About

A stupid simple linear state machine lib for running a sequence of queries on a mysql db within a rails 2.3.x context.

Puttin this up to share with some folks who were curious.

We (Academic Support Resources, University of Minnesota) use it as part of our OracleToMysqlBuilder ETL package (not-open-source yet, ask if interested) to transform mirrored data from Oracle in MySQL

Install

git submodule add git://github.com/joegoggins/mysql_db_builder.git lib/db_builder

Assumptions

• You have your db setup already
• You are using ActiveRecord

Usage

Given class Example < DbBuilder::Base def set_target_table @target_table = 'example' end

  def set_target_db
    @target_db = 'test'
  end

  def set_source_db
    @source_db = 'test'
  end
  def set_queries
    @queries << DbBuilder::Q.new(
    'create it',"yeppers",<<-END_OF_QUERY
    create table #{self.target_db}.#{self.target_table} (id int)
    END_OF_QUERY
    )
    
   @queries << DbBuilder::Q.new(
    'insert it',"yeppers",<<-END_OF_QUERY
    insert into #{self.target_db}.#{self.target_table} values (1)
    END_OF_QUERY
    )

    @queries.last.query_method = :insert_sql # :update_sql also available
  end
end

In the console x=Example.new => #<Example:0x226bbd0 @verbose_mode=true, @queries=[], @debug_mode=true, @on_exception=:raise>

puts x.to_s 
==========================================================================
Q0 :create it => (yeppers)

    create table test.example (id int)

==========================================================================
==========================================================================
Q1 :insert it => (yeppers)

    insert into test.example values (1)

==========================================================================

x.execute 
[Example][Q=create it]
    create table test.example (id int)
      
      
[Example][Q=create it] Does Not Exist: example
[Example][Q=create it] After Count: 0
[Example][Q=insert it]
    insert into test.example values (1)
      
      
[Example][Q=insert it] Before Count: 0
[Example][Q=insert it] After Count: 1
[Example][Q=insert it] Insert Statement last insert id 0
=> true

More Stuff

Use Lamda::Q for dynamicish "queries" in set_queries that involve Ruby in response to results from sql queries. Here's an example

@queries << DbBuilder::LambdaQ.new(
      :loop_for_every_layer_of_management,
      "Build position lineage, This needs to execute once for every 'layer of management' at the U. Just loop until nothing is affected.",
      lambda {
        affected_rows = 1 # start with non-zero
        while affected_rows > 0
          update_statement = "
            update #{self.target_db}.#{table_namer.temp} lineage
              left join #{self.target_db}.eff_ps_position_data position on 
                lineage.position_nbr=position.position_nbr
              left join #{self.target_db}.eff_ps_position_data supervisor_position on 
                position.reports_to=supervisor_position.position_nbr
              left join #{self.target_db}.#{table_namer.temp} supervisor_lineage on 
                supervisor_position.position_nbr=supervisor_lineage.position_nbr
            SET 
              lineage.lineage=concat(supervisor_lineage.lineage, '.', supervisor_position.position_nbr)
            WHERE 
              supervisor_lineage.lineage is not null
              and lineage.lineage is null
          "
          affected_rows=ActiveRecord::Base.connection.update(update_statement)
        end
      }
    )