Finding unique matches between two tables

This may be very simple, but I'm getting my feet tangled within Rails. How do I find the unique matches (same name, dob, ssn) between two tables?

CREATE TABLE "patientsingm" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "last" varchar(255), "first" varchar(255), "displayed_name" varchar(255), "sex" varchar(1), "dob" date, "ssn" varchar(12), "account" varchar(15) );

CREATE TABLE "pacspatients"   (   "id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,   "pat_ckey" varchar(12),   "pat_uid" varchar(50),   "pat_name" varchar(255),   "birth_date" varchar(10),   "sex_code" varchar(1),   "identifier" varchar(12)   );

class GMPatient < ActiveRecord::Base   establish_connection "gm"   set_table_name "patientsingm" end

class SybasePatient < ActiveRecord::Base   establish_connection "sqlitepacs"   set_table_name "pacspatients" end

Essentially.. How do I perform the 'AND' Set operation between those two?

This may be very simple, but I'm getting my feet tangled within Rails. How do I find the unique matches (same name, dob, ssn) between two tables?

class GMPatient < ActiveRecord::Base establish_connection "gm" set_table_name "patientsingm" end

class SybasePatient < ActiveRecord::Base establish_connection "sqlitepacs" set_table_name "pacspatients" end

If they are two separate databases then you'll probably have to do this mostly in ruby (ie grab a record from one table then see if it exists in the other table). If both tables were in the same database you could probably write this as a join, but not if the tables are not in the same database

Fred

Frederick Cheung wrote:

If they are two separate databases then you'll probably have to do this mostly in ruby (ie grab a record from one table then see if it exists in the other table). If both tables were in the same database you could probably write this as a join, but not if the tables are not in the same database

Fred

In short - there's no clean way in Rails to do this? It's a pure SQL solution? How do I execute pure SQL from within Rails? Do I have to use DBI?

I can definitely put both tables in the same database; my original choice of making it two separate databases did little besides teach me how to connect to more than one database with Rails :wink: This is all read only data anyway.

Frederick Cheung wrote: > If they are two separate databases then you'll probably have to do > this mostly in ruby (ie grab a record from one table then see if it > exists in the other table). If both tables were in the same database > you could probably write this as a join, but not if the tables are not > in the same database

> Fred

In short - there's no clean way in Rails to do this? It's a pure SQL solution? How do I execute pure SQL from within Rails? Do I have to use DBI?

YourModel.connection.execute

But you can't do it with pure sql if the tables are in different databases. Of course the ultimate solution to finding matches between two tables like this is to not need to in the first place - organise your data so that it isn't duplicated.

Fred

Frederick Cheung wrote: