TAILIEUCHUNG - Beginning Database Design- P4

Beginning Database Design- P4:This book focuses on the relational database model from a beginning perspective. The title is, therefore, Beginning Database Design. A database is a repository for data. In other words, you can store lots of information in a database. A relational database is a special type of database using structures called tables. Tables are linked together using what are called relationships. You can build tables with relationships between those tables, not only to organize your data, but also to allow later retrieval of information from the database | Database Modeling in the Workplace Converting Legacy Databases Converting legacy databases can often be the most difficult of tasks. Sometimes the databases are partially inaccessible or difficult to access at best. Sometimes the databases may even be in existence using network or even hierarchical database modeling techniques. These database model structures can be extremely large and complex and therefore very difficult to decipher. As with a paper system find someone who knows all about the database to help you otherwise dig into the database yourself allow plenty of time for analysis and verify structure. In the worst case analyze applications as well as the database model to confirm the operational functionality of the database and that it actually does what it should do. It could very well be the case that a new database model is required because the legacy database and software was incorrectly built in the first place or that requirements have drastically changed since its inception. If things have changed you should find someone or something that makes these differences very obvious either inside or outside of the database and applications or both. It s better to find an expert in the company first. Once again you will get much farther much faster and with much more ease by talking to people and asking questions. Homogenous Integration of Heterogeneous Databases In scientific terms a heterogeneous system is a system consisting of dissimilar parts. And obviously a homogenous system is the complete opposite consisting of similar parts or parts being of a uniform structure throughout. In terms of database models some of the much more sophisticated largely very expensive database engines allow for the creation of homogenous integration of heterogeneous databases. In other words it is possible to transparently link multiple types of databases using different database engines perhaps even including legacy databases and really any type of database that can be .

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