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SQL Normalization Database Design. Lecture 5. SQL Normalization Database Design. 1 st Normal Form 2 nd Normal Form 3 rd Normal Form Boyce-Codd Normal Form (BCNF) 4 th Normal Form 5 th Normal Form 6 th Normal Form Domain Key Normal Form (DKNF).

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## SQL Normalization Database Design

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**SQL NormalizationDatabase Design**Lecture 5**SQL NormalizationDatabase Design**• 1st Normal Form • 2nd Normal Form • 3rd Normal Form • Boyce-Codd Normal Form (BCNF) • 4th Normal Form • 5th Normal Form • 6th Normal Form • Domain Key Normal Form (DKNF)**SQL NormalizationDatabase Design: 1st Normal Form**• 1st Normal Form has 8 rules: • Rows contain data for instances of an entity. • Columns contain attributes that describe the data of an entity or its domain. • Attributes in a given row, also known as a cell in spreadsheets, contain a single value. • All attributes define data by a single data type. • All attributes have a unique name in an entity. • Attributes are arbitrarily ordered. • Rows of data have no implicit or explicit ordering to access or use. • Two rows may not contain duplicate data.**SQL NormalizationDatabase Design: 1st Normal Form**• 1st Normal Form: • Summary: A list of columns that (a) contain only an instance of a data type; and (b) define a collectively unique row. • Design Key #1: A single instance means that delimited values are not stored into a column, like a comma separated values (CSV) list. • Design Key #2: All columns taken together define a unique key that identifies a data structure.**SQL NormalizationDatabase Design: 2nd Normal Form**• 2nd Normal Form: • Summary: A row is in 2nd normal form when the list of all non-key columns (or attributes) are fully dependent on the list of key columns, and the row meets the definition of 1st normal form. • Design Key #1: The list of key columns defines the natural key that identifies a unique row. • Design Key #2: A surrogate key (e.g., an automated numbering sequence) may replace the natural key.**SQL NormalizationDatabase Design: 3rd Normal Form**• 3rd Normal Form: • Summary: A row is in 2nd normal form when (a) there is no transitive dependency, which is a functional dependency; and (b) the row meets the definition of 2nd normal form. • Design Key #1: A functional dependency means that the domain is a super domain of two domains, and deleting a row from the base domain removes an instance from the functionally dependent domain. • Design Key #2: Functional dependencies can cause deletion anomalies.**SQL NormalizationDatabase Design: 3rd Normal Form**• Functional Dependency: • A 2nd normal table exists when the domain contains both: • A RENTAL_ID that identifies two domains – the item rented and its rental price. • A deletion of RENTAL_ID 991 results in deleting the rental and the item rental price. • The ITEM_ID column is a functional dependency or transitive dependency. • Create two 3rd normal form tables by dividing the table into its separate domains. • The ITEM_ID becomes the primary key in one table and foreign key in the other.**SQL NormalizationDatabase Design: 3rd Normal Form**• Functional Dependency Resolution: • The ITEM_ID column becomes a primary key and unique description of any row in a 3rd normal form table. • The CHARGE column becomes wholly dependent on the new primary key. • The RENTAL_ID column remains the primary key of a reduced domain and the ITEM_ID becomes a foreign key to the new 3rd normal form table. • The functional dependency of RENTAL_IDCHARGE is eliminated.**SQL NormalizationDatabase Design: BCNF**• Boyce-Codd Normal Form (BCNF): • Summary: A row is in BCNF when (a) relations have a single determinant as a candidate key; and (b) the row meets the definition of 3rd normal form. • Design Key #1: A determinant lets you identify a row by combining it with one or more other columns to find a unique row in a relation, which is also known as a super key. • Design Key #2: A determinant is one or more attribute that does not qualify as a candidate key for a table but defines an internally or externally unique relation for a table.**SQL NormalizationDatabase Design: BCNF**• Determinant Problem: • A 3rd normal table exists when the domain contains both: • A RENTAL_ID that identifies two domains – the item rented and its type – DVD or VHS. • A deletion of RENTAL_ID 991 results in deleting the rental and the VHS item TYPE of a TITLE. • The TYPE and TITLE column are only inserted when there is a RENTAL_ID, which means the type of rental cannot be inserted before it is rented. • Create two BCNF tables by dividing the table into its separate domains.**Summary**• 1st Normal Form • 2nd Normal Form • 3rd Normal Form • Boyce-Codd Normal Form • 4th Normal Form • 5th Normal Form • 6th Normal Form • Domain Key Normal Form (DKNF)

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