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The College of Saint Rose CIS 521 / MBA 541 – Introduction to Internet Development David Goldschmidt, Ph.D. selected material from Fluency with Information Technology, 4th edition by Lawrence Snyder, Addison-Wesley, 2010, ISBN 0-13-609182-2
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A database stores data in an organized and electronic form Users typically see query results
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A database consists of: tables, columns or fields, rows (of data), etc.
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Example table in a relational database:
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To define a table, define each column or field Specify column name, data type, and a comment Also specify “keys” to the table for fast lookups
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select Name, Area from Island where Area > 1000 select Name, Area, Elevation from Island where Area > 500 and Elevation > 1000 order by Name
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Relationships (or associations) between tables define the structure of the data One-to-one relationship: course-offerings crn course-name course-number section locationid enrollment max-enrollment locations id building room max-seats 1 1
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Add a one-to-many relationship (* is many) course-offerings crn course-number course-name section locationid enrollment max-enrollment locations id building room max-seats 1 1 courses course-number course-name description credits 1 *
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How about a many-to-many relationship Imagine a database for an online shopping site Many products in many shopping carts! products-to-carts productid cartid quantity shopping-carts id username status * 1 products id name description sku price 1 *
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