Tag: databases

Questions Related to databases

What are some benefits of using a USI?

technology databases

  1. They eliminate Full Table Scans.

  2. Duplicate row checks are avoided.

  3. There is no overhead involved.

  4. They are best used for range queries.

  5. You cannot insert rows with a duplicate USI value.

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Correct Option: A,B,E

Data type assignments should be made at the row level to avoid data conversion.

technology databases

  1. True

  2. False

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Correct Option: B

What is one significant aspect about a Cover Query?

technology databases

  1. All columns required by the query are available via the Primary index.

  2. All columns required by the query are available via a Join Index.

  3. All columns required by the query are available via the Hash Index

  4. The PE covers the query by looking into cache to see if the same query has been run in the last 240 minutes. If it has been cached the PE doesn't have to generate steps for the AMPs.

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Correct Option: B

Select two true statements about Join Indexes. (Select 2)
technology databases

  1. Join Indexes have repeating values.

  2. Join Indexes do not have repeating values.

  3. Join Indexes are updated automatically when their underlying rows change

  4. Join Indexes are not updated automatically when their underlying rows change.

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Correct Option: A,C

When denormalizing a table, what are some things to consider? (Select 2)

technology databases

  1. Downtime

  2. Stability

  3. Performance

  4. Volatility

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Correct Option: C,D

The OR operator displays a record if both the first condition and the second condition is true.

technology databases

  1. True

  2. False

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Correct Option: B

Which operator allows you to specify multiple values in a WHERE clause?

technology databases

  1. BETWEEN

  2. IN

  3. HAVING

  4. ALIAS

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Correct Option: B

The UNION operator is used to combine the result-set of two or more SELECT statements when

technology databases

  1. each SELECT statement within the UNION has the same number of columns

  2. The columns have similar data types

  3. the columns in each SELECT statement are in same order.

  4. None

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Correct Option: A,B,C

Which of the following are Scalar functions?
technology databases

  1. MAX( )

  2. MID( )

  3. SUM( )

  4. NOW( )

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Correct Option: B,D

WHERE keyword could not be used with aggregate functions.
technology databases

  1. True

  2. False

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Correct Option: A