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This chapter is from the book
Practice exam questions
The following practice exam questions test your knowledge of material that this chapter covers.
| 1: |
Which statement about domains is false?
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By defining a domain for a particular attribute, you apply business rules to ensure that the data will make sense.
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A domain describes the conditions that an attribute value must meet to be a valid value.
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A domain can identify a range of valid values.
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None of the above; all statements are true.
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| 2: |
Which numeric data type is defined correctly?
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REAL data consists of single-precision floating-point numbers that are greater than 21.
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DOUBLE data is two-digit data in double-precision floating point numeric format.
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SMALLINT data is an integer less than 22.
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INTEGER data is for large integers.
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| 3: |
Which two statements about null values are true?
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Depending on user-defined settings, the DBMS can treat a null value as a zero value, a blank, or an empty string.
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A null value is a special indicator that represents the absence of a value.
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A null value is equivalent to a blank.
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For an attribute that does not need to have a valid value at all times, use a null value.
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A null value is equivalent to a zero value.
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| 4: |
Which statement is false?
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If a DBMS uses an index to find a row in a table, the performance is always better than when the DBMS scans the entire table.
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A table with a unique index can never have two rows with the same values in the columns that form the index key.
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A clustering index keeps table rows in a specified sequence, which always minimizes page access for a set of rows.
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All of the above.
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| 5: |
Which statement about designing indexes is false?
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During physical database design, you decide what indexes to define on what columns of a table.
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You can use process models to determine how different applications and users will be accessing data.
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Users of a table with an index are generally aware that an index exists on the table.
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Decisions about indexes are important because of the performance implications they present.
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| 6: |
Which statement does not explain a purpose of an index?
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An index can be used to optimize data access.
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An index can be used to ensure uniqueness.
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An index can be used to enable clustering.
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None of the above; all statements are correct.
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