Although revised in 1999 (usually referenced as SQL or SQL), most vendors are still not fully compliant with the 1992 version of the standard. The 1992 standard is smaller and simpler to reference for a user, and since only some of the 1 999-specific requirements are typically implemented at this time, it may be a better starting point for learning the language. 1. 1 A data model is a conceptual representation of the data structures that are required by a database. The data structures include the data objects, the associations between data objects, and the rules which govern operations on the objects.
As the name implies, the data model focuses on what data is required and how it should be organized rather than what operations will be performed on the data. To use a common analogy, the data model is equivalent to an architect’s building plans. A data model is independent of hardware or software constraints. Rather than try to represent the data as a database would see it, the data model focuses on representing the data as the user sees it in the “real world”. It serves as a bridge between the concepts hat make up real-world events and processes and the physical representation of those concepts in a database.
Galena Manifesto 1. 1. 1 Methodology There are two major methodologies used to create a data model: the Entity- Relationship (ERE) approach and the Object Model. This document uses the Entity-Relationship approach. 1. 1. 2 Data Modeling In the Context of Database Design Database design is defined as: “design the logical and physical structure of one or more databases to accommodate the information needs of the users in an organization for a defined set of applications”.