May 6, 2018 at 2:22 pm
Hello. I was watching a video that covered Normalization. It explained that a database is in third normal form when first and second normal form have been met and all the columns in a table depend on the primary key. I couldn't make any sense out of what the author of this video meant by all the columns in a table depend on the primary key. Any help would be greatly appreciated. Thanks !!!
May 7, 2018 at 1:13 am
Ronnie65 - Sunday, May 6, 2018 2:22 PMHello. I was watching a video that covered Normalization. It explained that a database is in third normal form when first and second normal form have been met and all the columns in a table depend on the primary key. I couldn't make any sense out of what the author of this video meant by all the columns in a table depend on the primary key. Any help would be greatly appreciated. Thanks !!!
The short version is that the conditions are met when any single attribute value cannot be duplicated by changing the value of another attribute, i.e. same person entered with different birthdays or address etc.
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May 7, 2018 at 7:45 am
Please post DDL and follow ANSI/ISO standards when asking for help.
May 7, 2018 at 9:01 am
Ronnie65 - Sunday, May 6, 2018 2:22 PM"Database Design and Relational Theory: Normal Forms and All That Jazz" by C. J. Date is the best discussion of Normal Forms I have found.
+100
All of Christopher's work is an excellent read on the subject
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May 7, 2018 at 9:43 am
Eirikur Eiriksson - Monday, May 7, 2018 1:13 AMRonnie65 - Sunday, May 6, 2018 2:22 PMI don't understand your last paragraphThe short version is that the conditions are met when any single attribute value cannot be duplicated by changing the value of another attribute, i.e. same person entered with different birthdays or address etc.
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May 16, 2018 at 12:19 pm
Ronnie65 - Sunday, May 6, 2018 2:22 PMHello. I was watching a video that covered Normalization. It explained that a database is in third normal form when first and second normal form have been met and all the columns in a table depend on the primary key. I couldn't make any sense out of what the author of this video meant by all the columns in a table depend on the primary key. Any help would be greatly appreciated. Thanks !!!
If the video you were watching was specific to the 3rd Normal Form, that deals with the concept of "transitive dependencies"...
In short, it simply means that an attribute (non key column) must be fully dependent on the primary key and not, in any way, dependent on any other non-key attribute.
The classic example is that of a "book" table (relation) that has ISBN" as the primary key and includes "Author" and "AuthorNationality" as attributes (non PK columns). In this example, The inclusion of "AuthorNationality" violates the 3rd NF because it is an attribute of the books author, not the book itself... aka AuthorNationality is only transitively dependent on the books ISBN.
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