Lecture 07 - Physical Design.pdf

Pine valley furniture company lee 758y 05 7 usage

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(Pine Valley Furniture Company) Lee-758Y-05 7 Usage analysis: 14,000 purchased parts accessed per hour è 8000 [email protected] accessed from these 14,000 purchased part accesses è 7000 suppliers accessed from these 8000 [email protected] accesses
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Figure 5-1: Composite Usage Map (Pine Valley Furniture Company) Lee-758Y-05 8 Usage analysis: 7500 suppliers accessed per hour è 4000 [email protected] accessed from these 7500 supplier accesses è 4000 purchased parts accessed from these 4000 [email protected] accesses
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Designing Fields § Field : smallest unit of [email protected] data recognized by system sobware. § Field design : Choosing data type. Coding, compression, [email protected] Controlling data integrity. Lee-758Y-05 9
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Table 5-1: Choosing Data Types Lee-758Y-05 10 VARCHAR(n) INTEGER DECIMAL(p[,s]) REAL FLOAT
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Figure 5-2: Example of a Code Look-Up Table (Pine Valley Furniture Company) Lee-758Y-05 11 Code saves space, but costs an [email protected] lookup to obtain actual value.
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Field Data Integrity § Default value – assumed value if no explicit value. § Range control – allowable value [email protected] (constraints or [email protected] rules). § Null value control – allowing or [email protected] empty fields. § Referen8al integrity – range control (and null value allowances) for foreign-key to primary-key match-ups. Lee-758Y-05 12
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Handling Missing Data § [email protected] an [email protected] of the missing value (e.g., using a formula). § Construct a report [email protected] missing values. § In programs, ignore missing data unless the value is significant ([email protected] [email protected]).
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  • Fall '18
  • AdamLee
  • Data Management, Relational model, Database management system

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