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Questions Related to technology

Multiple choice technology databases

In a query, Table_A is joined with Table_B based on the join criteria (Table_A.Column_1 = Table_B.Column_1). The SME in the team mentions that Table_B is the child of Table_A based on Column_1 (one-to-many relationship) and should always have value. Given these considerations, which of the following doesn't apply to this situation?

  1. There needs to be a Foreign Key relationship between the two tables.

  2. Table_B.Column_1 shouldn't have NULL values.

  3. There should be a clustered index on Table_A.Column_1 and a non-clustered index on Table_B.Column_1.

  4. Table_B.Column_1 should be unqiue.
Reveal answer Fill a bubble to check yourself
D Correct answer
Full explanation
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