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Terms - data,information, file record, table, row, column, transaction, concurrency Concepts - data integrity, data redundancy, Type of databases – single-user, shared, etc. Meta data versus actual operational data Functions of a DBMS 1.Data Dictionary Management 2.Data Storage Management 3.Data presentation ( access through SQL) 4.Security 5.Multi-User (transaction) 6.Back-up and Recovery (stores multiple versions) Data Models 1.Attributes 2.Relationships (1-1, 1-many) 3.Constraints Using Access 1.Different views – Dataview, Datasheet 2.Declaring column datatypes 3.Primary keys 4.Relationship diagrams 5.Cascade deleting BACKGROUND
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Definition – Remove redundancies by segmenting and eliminating dependencies Normal Forms 1 st Normal – No repeating fields 2 nd Normal – No partial dependencies 3 rd Normal – No transitive dependencies NORMALILZATION Column Select - rename column with AS - * means all columns - [ ] for column name with embedded spaces Use of aggregate functions FROM Join tables, rename tables WHERE RELATIONAL ALGEBRA comparisons Can implement logical join GROUP BY Creates Summary Record Having is similar to where clause ORDER BY (sort criteria) ASC or DESC SQL SELECT STATEMENTS
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3 Steps in normalization
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4 Table with multivalued attributes, not in 1 st normal form
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5 Table with no multivalued attributes and unique rows, in 1 st normal form
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6 Order_ID Order_Date, Customer_ID, Customer_Name, Customer_Address Therefore, NOT in 2 nd Normal Form Customer_ID Customer_Name, Customer_Address Product_ID Product_Description, Product_Finish, Unit_Price Order_ID, Product_ID Order_Quantity Functional dependency diagram for INVOICE
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7 Partial dependencies are removed, but there are still transitive dependencies Getting it into Second Normal Form Figure 5-28 Removing partial dependencies
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8 Third Normal Form 2NF PLUS no transitive dependencies (functional dependencies on non-primary-key attributes) 2NF PLUS no transitive dependencies (functional dependencies on non-primary-key attributes) Note: This is called transitive, because the primary key is a determinant for another attribute, which in turn is a determinant for a third Note: This is called transitive, because the primary key is a determinant for another attribute, which in turn is a determinant for a third Solution: Non-key determinant with transitive dependencies go into a new table; non-key determinant becomes primary key in the new table and stays as foreign key in the old table Solution: Non-key determinant with transitive dependencies go into a new table; non-key determinant becomes primary key in the new table and stays as foreign key in the old table
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