From the course: Database Foundations: Data Structures

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Third normal form

Third normal form

From the course: Database Foundations: Data Structures

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Third normal form

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- [Instructor] Once we've checked our tables to ensure that they satisfy both 1NF and 2NF, we can turn our attention to satisfying the third normal form. 3NF starts with the assumption that the table is in second normal form, and then adds the requirement that every field is non-transitively dependent on the primary key, or the unique identifier, for each row. This ensures that the data contained in an attribute column is not determined by another field that is not part of the key. This typically includes calculations and other kinds of derived data. To see an example of this, let's add some new columns to the Pets table. I've modified the table to include a column to store each pet's age and the scientific name of their species. To find out if the table is in third normal form, we need to ask if every column is dependent on the unique identifier. What we're looking for are columns that have a value that's dictated…

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