say you have two databases
db1=DAL(...)
db2=DAL(...)
and they contains a similar table
table1=db1.define_table('person',Field('name'))
table2=db2.define_table('person',table1) # same fields a table1
and you want all records from both
rows=db(table1.id>0).select()&db(table2.id>0).select()
now you can sort them by name
rows=rows.sort(lambda row: row.name)
or you can get all records without duplicates
rows=db(table1.id>0).select()|db(table2.id>0).select()
and filter those that start with 'a'
rows=rows.find(lambda row: row.name.startswith('a'))
etc.
The last 4 operations are performed at the web2py level, not the db
level so they may use lots memory and IO.
Massimo
On Oct 2, 3:59 am, Alexandre Andrade <alexandrema...@gmail.com> wrote:
> (this text was translated by google)
>
> Hi folks,
>
> I'll have to develop an application on my service that uses data from
> several databases.
>
> I'm the one time looking for a way to solve this problem within the web2py
> and the solution is pictured below.
>
> I wonder if anyone has a similar situation and considerations that would
> have the following possible solution:
>
> --------------------------------------------------
> --------------------------------------------------
> ------------------
>
> A Universal Interface for Databases is a webservice that centralizes access
> to all databases of a company.
>
> Although in most cases applications use only one database, on the whole, a
> company has multiple databases.
>
> In many cases they are redundant and have duplicate information in several
> ways.
>
> This means that in practice, developers or duplicate the information have to
> create ad hoc solutions to integrate systems.
>
> This also requires that to generate management information, there is a need
> to create "data warehouses" to gather all the information and extract
> reports.
>
> The purpose of the UDI is to serve as sole access to all information from
> all databases of the company.
>
> Thus, the developer connects your application to a single point, and calls
> through the UDI all the information your application needs, as well as
> forward all information necessary for the UDI provide storage.
>
> The functions of the IDU are:
>
> 0. Manage the connection and communication with all legacy databases.
> 1. List all databases, tables and data fields available, with metadata, if
> any
> 2. Allow queries that retrieve information from different databases, as if
> they were one (least of records)
> 3. Let me set the mapping between the data required by the application
> with the various databases in a visual interface, even to the programmer.
> 4. Store information received as a single record distributing it in
> different fields of databases and tables if needed.
> 5. Setting a standard database application, which will store the mappings
> of the data with all other existing databases, and to store the application
> specific data, not available elsewhere.
> 6.Possuir a tool for generating reports and dashboards for nontechnical
> users.
>
> In web2py, it would be a standalone application as well as the admin, and
> would be used in applications as a substitute for DAL, yet remains easy to
> generate the forms.
>
> The big difference, and allows using data from several sources, is that the
> data (tables and fields) present in other banks would not need to be
> defined, but only mapped, and both the mapping and the possible creation of
> tables and fields would be in a graphical interface.
>
> --
> Atenciosamente
>
> --
> =========================
> Alexandre Andrade
> Hipercenter.com
