Jorge alejandro Mendoza torres wrote:
> Hello.
> 
> I need to do a query with various tables, but I want to use something
> like find_by_sql.
> 
> It's say, i want to make the next query:
> 
> SELECT field_table1,field_table1,field_table2
> FROM table1, table2
> WHERE table1.id=table2.table1_id

It depends on what database access library you are using. There are many 
to choose from; there are direct native APIs to most databases, or the 
low-level DBI which wraps these. They'll all work at the level of SQL 
statements like SELECT.  Then there are higher-level abstractions like 
ActiveRecord, Sequel, DataMapper, og, ...

"find_by_sql" sounds like something from ActiveRecord.

If your question is specifically about ActiveRecord, you might be better 
of asking in a Rails mailing list.
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