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Microsoft® SQL Server™ 2000 Programming by Example by Carlos Eduardo Rojas, Fernando G. Guerrero

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Creating and Altering Tables

The first step in the databasedesign process is creating the entity relationship model, which is a conceptual representation of the database. The entity relationship model is comprised of entities, attributes, and relationships. An entity represents a real-world object, such as cars, employees, orders, students, courses, and teachers. Each entity has characteristics,which are called attributes. For example, the entity called employee has these attributes: Social Security number (SSN), last name, and first name. The last piece is the relationship, which is a link between two or more tables. There are three types of relationships: one-to-one (1:1), one-to-many (1:M), and many-to-many (M:N). For example, there's a one-to-many ...

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