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10 Cards in this Set
- Front
- Back
What are the steps for taking a table and splitting it up for use in a database?
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Follow the steps of normalization!
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How do you determine the number of rows in a database using SQL
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SELECT COUNT(*) as NumOfRows
FROM Inventory |
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How do you show all columns and rows of a table using SQL?
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SELECT *
FROM Inventory |
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How do you use the top/limit clause in SQL?
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SELECT *
FROM Inventory LIMIT 10; |
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What are the advantages of normalization?
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-Greater overall database organization
-Reduction of redundant data -Data consistency within the database -A much more flexible database design -A better handle on database security |
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What are the disadvantages of normalization?
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-It requires much more storage space.
-Requires more joins to get certain data displayed. -More data = more tables (i.e. more work). |
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Why would you denormalize a set of tables?
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To maintain a history and/or to improve performance.
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What is the multivalue, multicolumn problem?
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The number of items ends up being fixed (i.e. have columns for 3 children but someone has 4), and it presents the problem of having to write a more complicated query.
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What is a null value, and what problems does it present in database design?
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Null technically means "unknown" so it really can't be considered a value. It can present problems if a table contains mathematical operations b/c null has an unknown value and therefore you cannot complete the operation. It can also adversely effect aggregate functions like COUNT.
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What is the problem with general purpose remarks in SQL?
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They typically contain inconsistent data. What one person thinks may be very different from another or they may choose different keywords. This causes a major quandry for someone who may be writing a query.
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