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7 Cards in this Set
- Front
- Back
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What are the mathematical branches that the relational model is based on?
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Set theory and predicate logic.
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What is the difference between T-SQL and SQL?
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SQL is standard; T-SQL is the dialect of and extension to SQL that Microsoft implements in its RDBMS—SQL Server.
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Name two aspects in which T-SQL deviates from the relational model.
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A relation has a body with a distinct set of tuples. A table doesn’t have to have a key. T-SQL allows referring to ordinal positions of columns in the ORDER BY clause.
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Explain how you can address the two items in question 1 and use T-SQL in a relational way.
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Define a key in every table. Refer to attribute names—not their ordinal positions—in the ORDER BY clause.
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Why are the terms “field” and “record” incorrect when referring to column and row?
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Because “field” and “record” describe physical things, whereas columns and rows are logical elements of a table.
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Why is the term “NULL value” incorrect?
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Because NULL isn’t a value; rather, it’s a mark for a missing value.
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Why is it important to use standard SQL code when possible and know what is standard and what isn’t? (Choose all that apply.) a) It is not important to code using standard SQL. b) Standard SQL code is more portable between platforms. c) Standard SQL code is more efficient. d) Knowing what standard SQL code is makes your knowledge more portable. |
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