Tag: databases

Quizzes (243) Questions (4862)

Questions Related to databases

Multiple choice technology databases

In Accounts_History table, among many columns, I have the Account_ID (Primary Key) and Trans_Date. There is a query that runs frequently to know the latest transaction that was done on the account. Which one of the below approaches will be most beneficial in this case?

  1. Defining a clustered index on Account_ID

  2. Defining a clustered index on Account_ID, Trans_Date

  3. Defining a non-clustered index on Account_ID, Trans_Date

  4. Don't define any indexes
Reveal answer Fill a bubble to check yourself
B Correct answer
Full explanation
Multiple choice technology databases

There are 10 tables with similar structure but mutually exclusive records. A query needs to fetch some records from each of these tables. Which of the following is the best approach to do this?

  1. Use UNION between the 10 SELECT statements

  2. Execute separate SQL statements and let the front-end merge the results

  3. Use UNION ALL between the 10 SELECT statements

  4. Define a temporary table and populate it with data from the 10 SELECT statements and then do a single SELECT from this table
Reveal answer Fill a bubble to check yourself
C Correct answer
Full explanation