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DatabaseDesign&SQL

Normailization

QuestionAnswer
1st Rule Of Normalization Eliminate Repeating Groups (of columns by making another table)
Why is the first rule of normalization so important? Execution Speed and Scalability
Give an example of a table with repeating groups of columns TTeams intTeamID strTeam strPlayer01FirstName strPlayer01LastName ... strPlayer10FirstName strPlayer10LastName
What do you do if you have nested groups of repeating columns? Collapse all nested repeating groups and apply the 1st rule of normalization one level at a time.
A Identify the repeating groups.
B Determine how many groups there are, how many times each group repeats and how many columns are in each group.
C Collapse nested repeating groups and fix them one level at a time. Next repeating groups usually have two sets of numbers in the column names.
D For each set of repeating groups create a new table.
E Into the new table(s) copy ***all of the primary key columns*** from the original table and make them part of the primary key in the new table(s).
F In the new table (s) create an integer index column and make it part of the primary key. That will make a primary key constraint with at least two columns.
G For each repeating group take one set of repeating columns from the original table and add them to the appropriate new table.
H Remove the number from the column names in the new tables.
I Remove the repeating group (s) from the original table.
J To name the new table (s) use the complete name of the original table plus a word or phrase that describes the group of repeating columns. Replace the ? in the index column with the descriptive word or phrase.
Created by: 3dsommer3