About RDBMS Concept.
Can any give me overview of Entity,attribute,Tuples and Domain set. and E-R Model Diagram and 1st,2nd and 3rd Normalforms. ...
rdbms
The difference between a 'view' and 'base' relation
What is the difference between a 'view' and 'base' relation in database systems? ...
RDBMS data-relation burden
Our in-house system is built on SQL Server 2008 with a 40-table 6NF schema. Most of the tables FK to 3 others, a key few as many as 7. The system will ultimately support 100s of employees working with 10s of 1000s of customers and store 100s of 1000s of transactional records -- prime-time access should peak at 1000 rows per second. Is...
Help me to connect inheritance and relational concepts
I was talking with a programmer pal of mine about inheritance and its use in designing models. He's a big proponent and I'm a little more tepid. Mostly because I tend to design systems from the bottom up: Database -> Application -> Presentation (honestly, I'm not much of a front-end guy, so I often leave presentation entirely to someone ...
Why aren't OODBMS as widespread as RDBMS?
Why are relation databases more common than object-oriented databases? If the Object Oriented Programming paradigm is so widespread, shouldn't we see lots of OODBMS? Wouldn't they perform better than the RDBMS+OR/M? ...
What does Codd's 'non-subversion rule' mean?
Recently I was reading about Codd's 12 Rules, and I understood all except number 12, the 'non-subversion' rule. If anyone can explain me the rule (using an example, preferably), that would be very helpful. Thanks. ...
Why is Select 1 faster than Select count(*)?
In Oracle, when querying for row existence, why is Select 1 fast than Select count(*)? ...
Is there an official name for the many-to-many relationship table in a database schema?
Most of the projects I've worked on have required many-to-many relationships in the database schema. For example, you might have the concept of Users and Groups, and the database might contain a table User, a table Group, and a table UserGroup to relate the two. I'm interested in the conceptual name of the UserGroup table in that examp...
How to represent a self to self relationship in rdbms?
Hi, Hopefully this is a silly question but my brain is fried and I can't think of how to do it right now. I'm messing around trying to make a social networking thingy and will need to keep track of a person's "followers". I have a user table made already, but how do I represent the idea of users being associated with one another? This...
simplest fail over support for standard rdbms?
Currently I am working on failover support of an existing application. The application uses postgres to store data but does not use any special feature (view/trigger etc). The database is more of a configuration storage rather than real data storage. When the application starts, it loads the data in memory and seldom goes back to datab...
How to store data with dynamic number of attributes in a database
I have a number of different objects with a varying number of attributes. Until now I have saved the data in XML files which easily allow for an ever changing number of attributes. But I am trying to move it to a database. What would be your preferred way to store this data? A few strategies I have identified so far: Having one singl...
Microsoft SQL Server to Oracle Data Migration (Conversion) (Other RDBMS ok, too)
Hi all, Can you please give some tips or guidelines, best practices for MicroSoft SQL server to Oracle Data Migration? IMHO, it is something that comes best with experience. So I would like to benefit from your experience. Please share any insights that you have into design, modeling, testing or tuning for a data migration project. I wo...
Choosing between a directory server (a.k.a LDAP database) and an RDBMS
In my project, where I'm the lead developer, we earlier had a network configuration that was stored a single XML file. The configuration contains info about a network layout - its constituent hosts, various details about each host like OS, platform, users configured in each them, several attributes for each user and so on. In the forthco...
Spring RDBMS vs JDBCTemplate
How much of a performance difference is there between these two models? What kind of reasons are there for using one over the other? In my application I am using a lot of the same statements over and returning both Objects and primitives. There are a few oracle stored procedure calls and performance on these is a top priority. ...
How universal is the LIMIT statement in SQL?
I'm in the process of generalizing a Django DB replication app and it uses the statement: SELECT %s FROM %s LIMIT 1 to fetch 1 row and use the Python DBAPI to describe the fields, it works fine with ORACLE and MySQL but, how cross platform is the LIMIT statement? ...
Good Java application to learn OOD
Hi, I'm looking for an open source java application (C# application is also ok), to learn & understand good Object Oriented design. Specifically, I'm looking for interactions with relational database, so that I can understand the finer details between converting an OO design to non-OO structure. I had a look at some ORM samples. While...
Can Excel use itself as a Database?
I found an interesting article at MSDN, which says: ADO makes it possible to treat an Excel workbook as if it were a database. So is it possible for an Excel workbook to connect to itself, and treat one of its worksheets as a database table and execute queries on it? -- and is this possible via VBA programming? ...
Database "pointers" to rows?
Is there a way to have "pointers to rows" in a database? for example I have X product rows, all these rows represent distinct products but many have the same field values except their "id" and "color_id" are different. I thought of just duplicating the rows but this could be error prone, plus making a small change would have to be done...
Moving away from MS SQL Server to open source RDBMS
So I'm an MSSQL guy and I have been for a while because it's what I've always used in my workplaces. So when I create a new project I'm usually inclined to just grab a copy of SQL Express and start working from there. However, I've been asked to work on a new project but for various reasons, we can't use SQL Express edition and the lice...
Why don't the mainstream DBMSs have graph functionality?
Relational databases are frequently used to store graphs in all their many flavors (trees, directed graphs, undirected graphs, ...). Why then do none of the major DBMSs (Microsoft, MySql, Oracle, PostgreSQL, SqlLite, just to name a few in alphabetical order) include library support for treating relations as graphs? Some desirable featu...