I have 2 tables, "sims" (as in mobile phone sim cards) and "phones" (as
in mobile phones).  I can add any number of sim cards to the "sims"
table and any number of mobile phones to the "phones" table.  Simple enough.
Rule 1: A sim card can either be in a phone, or not in a phone.  ...

My book claims that for table to be in 1NF, we must:
* Eliminate remove repeating groups of data
* Create separate tables for each group of related data and identify
each row with a unique column ( the primary key )

I'm reading Elmasri & Navathe's "Fundamentals of Database Systems, 4th
ed.". The authors discuss how, given a set if FDs, additional FDs can
be inferred. The authors provide six "Inference Rules". At one point
the authors say this:

With DB2, you need to run "ACTIVATE DATABASE dbname" if you want a
database to remain active even when the last session disconnects. This
can make a big difference in order to cut down on connection setup times.
Does Informix have the same kind of mechanism/requirement, or is a

1) One site claims the following table is not in first normal form –
but the definition for 1NF just says that data shouldn’t  contain
repeating groups of fields. And it’s quite obvious that there are no
repeating columns in the following table, since I wouldn’t consider

The rules governing whether a given relvar coupled with dependency
rules are in a normal form are well defined.
Unfortunately, many of the FDs are actually business rules in the
designer's head, not easily expressed in the form FD A -> B etc.  The

I was thinking about it, and it seems like a large amount of operations
on an RDBMS are equivalent to map/reduce operations.
Does anyone know of any research in this area, or is this old news that
I'm just now finding?

I have a fundamental doubt regarding replication in databases.
If the isolation level is set to Serializable, why cant we just ship
the transaction statements from the master to the backup and replay
those transactions. Why do we adopt complicated solutions like log

I have a leasing system where customers rent items and pay them of
over time. This is somewhat different from the usual order/order_line
design since in this case the customer only have one order which is
then modified via extensions (i.e. as he extends the leasing periods,

First of all I can be said new at database stuff. I want to know how
to test MySQL and PostgresSQL. I had googled some and I am thinking of
using a monitoring tool. Any monitoring tool with graph reports like
jmeter?

I've inherited a single user application using a database (multiple
backends : Postgres, Firebird, Oracle) and need to bring it on par for
multi-users access.
Right now each DB operation (fetch a structure, update a record, ...) is

I just got this email today, from a well-placed acquaintance, passing on
an opportunity that greatly exceeds my ability to execute.  If anyone
reading this meagre outline feels  they might have the right background,
I'd be happy to pass on your email address.