Friday, 31 August 2007

MySQL DB Design Tutorial (Section 1) - Introductions

Ratio Scales (Ratio scales are what people think of when they think about a measurement)

  1. Ratio scales have an origin, an ordering, and a set of operations that can be expressed in arithmetic.
  2. They are called ratio scales because all measurements are expressed as multiples of fractions of a certain unit or interval.
  3. Examples: length, mass, and volume. (The unit is what is arbitrary; the weight of a bag of sand is still weight whether it is measured in kilograms or in pounds)
Relationship Checklist
  1. Make sure that each table in your database has been reviewed for possible relationships with other tables.
  2. For tables with relationships to other tables, make sure that the relationship has been properly identified. This would include: A. The type of participation between the tables; B. The degree of participation between the tables.
  3. Make certain that each foreign key meets the following best practice suggestions: A. The name of the foreign key should match the name of the primary key it is related to (a data element has only one and only one name in a schema); B. The column specifications of the foreign key are identical to those of the primary key.
Data Integrity Related Terms
  1. This level of integrity is a vital aspect of database design and the following lists some of the more important terms associated with integrity: A. Column Specification (general elements, physical elements, and logical elements); B. Data Integrity (table-level, column-level, and referential integrity)

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