07-01-2014, 04:12 PM
Codd’s Twelve Rules
Codd’s Twelve.ppt (Size: 84.5 KB / Downloads: 499)
Oracle’s grading scale
0 = doesn’t meet criteria
1/2 = meets some of the criteria
1 = meets the criteria
1. Information Rule
information is to be represented as data stored in cells
Vehicle Identification Number in one cell would violate this rule
paint color
body style
2. Guaranteed access rule
Each data item must be accessible by combination of
table name + primary key of row +column name
violation of rule--ability to access by using arrays or pointers
How does Oracle fair on the 1st two points?
BLOBs-Binary Large OBjects
early RDBMS technique to store and manage multimedia data types
typically stored outside the database (in files), and pointers are placed in their corresponding column positions
BLOBs push the 1st two rules
Implementation is transparent to the user
Do not explicitly break 1st two rules
Score 1 1/2
1/2 pt deducted for “bad conduct”
competitors grade out the same
Grade for rule 4
1/2
Oracle allows SELECT only, but INSERT, UPDATE, and DELETE are not possible
This probably should not occur frequently and may not even be desired, but it should be possible according to rule 4.
Final Grade
8 1/2 out of 12
give or take a point
Point is not the precision of final score
FACT--Oracle does not meet all of Codd’s 12 rules
Neither does Sybase nor Informix
It is a RDBMS
Oracle and its competitors have more work to do
Oracle 7 only fully passed rule 10