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Practice exam questions

The following practice exam questions test your knowledge of material that this chapter covers.

1:

Which statement about domains is false?

  1. By defining a domain for a particular attribute, you apply business rules to ensure that the data will make sense.

  2. A domain describes the conditions that an attribute value must meet to be a valid value.

  3. A domain can identify a range of valid values.

  4. None of the above; all statements are true.

2:

Which numeric data type is defined correctly?

  1. REAL data consists of single-precision floating-point numbers that are greater than 21.

  2. DOUBLE data is two-digit data in double-precision floating point numeric format.

  3. SMALLINT data is an integer less than 22.

  4. INTEGER data is for large integers.

3:

Which two statements about null values are true?

  1. Depending on user-defined settings, the DBMS can treat a null value as a zero value, a blank, or an empty string.

  2. A null value is a special indicator that represents the absence of a value.

  3. A null value is equivalent to a blank.

  4. For an attribute that does not need to have a valid value at all times, use a null value.

  5. A null value is equivalent to a zero value.

4:

Which statement is false?

  1. 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.

  2. A table with a unique index can never have two rows with the same values in the columns that form the index key.

  3. A clustering index keeps table rows in a specified sequence, which always minimizes page access for a set of rows.

  4. All of the above.

5:

Which statement about designing indexes is false?

  1. During physical database design, you decide what indexes to define on what columns of a table.

  2. You can use process models to determine how different applications and users will be accessing data.

  3. Users of a table with an index are generally aware that an index exists on the table.

  4. Decisions about indexes are important because of the performance implications they present.

6:

Which statement does not explain a purpose of an index?

  1. An index can be used to optimize data access.

  2. An index can be used to ensure uniqueness.

  3. An index can be used to enable clustering.

  4. None of the above; all statements are correct.

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