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17 Cards in this Set
- Front
- Back
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What is database normalization? |
A set of rules for organizing attributes & tables |
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What are three reasons for database normalization? |
Eliminates anomalies, minimizes redundancy, and improves database performance |
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What does first normal form require? |
All fields only include a single piece of data. |
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How is first normal form corrected? |
By adding a table with a one-to-many relationship |
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What does second normal form require? |
All non-key fields must be functionally dependent on every part of a composite primary key |
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What does third normal form require? |
All non-key fields are not functionally dependent on another non-key field. |
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What is denormalization? |
Knowingly violating a normalization form. |
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What are indexes? |
A copy of a column of data from a table that can be searched more efficiently. |
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Why use an index? |
Searching non-key values is slow, indexes speed up retrieval. |
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What are downsides to an index? |
Slows down updates, adds redundant data to a database, and increases the size. |
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Candidates for an index? |
Non-key fields that you need to search regularly, fields that change infrequently, and shorter fields. |
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What is a view? |
A "window" into a portion of the database (virtual table). |
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Why use a view? |
Maintain confidentiality by restricting access to certain parts of the database, and simplify frequently used queries. |
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Limitations of a view? |
No parameters, no sub-queries, and no table/data modifications. |
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What is a stored procedure? |
A set of SQL statements with an assigned name. Stored in the database in compiled form and can be shared by a number of applications. |
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Why use a stored procedure? |
Easy to maintain, faster than queries (pre-cached), and more secure. |
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Difference between views and stored procedures? |
Views are single, read-only select statements while stored procedures can be CRUD statements, multiple statements, parameters, and programming logic. |
