Tag: databases

Questions Related to 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?
technology databases

  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

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Correct Option: B

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?
technology databases

  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

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Correct Option: C

Always use hints while writing queries (e.g. WITH NOLOCK, WITH UPDLCK) since it will help the query optimizer

technology databases

  1. True

  2. False

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Correct Option: B

Please see the below query: create table employee (emp_id number(6) primary key, emp_name varchar2(20)); rollback; What will the result of the below query: desc employee;
technology databases

  1. It will describe the table.

  2. It will return ar error:'Table or view does not exist'

  3. The query is not correct.

  4. None of the above

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Correct Option: A

We can use group by clause with:
technology databases

  1. Non aggregate functions only

  2. Aggregate functions only

  3. Both 1 & 2

  4. None of the above

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Correct Option: B

Which of the below is the correct query to update the columns of a table:
technology databases

  1. update table TABLE_NAME set COMLUMN_NAME= where

  2. update TABLE_NAME set COMLUMN_NAME= where

  3. Both 1 & 2 are correct

  4. None of the above

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Correct Option: B

UNION query returns only distinct rows and UNION ALL may return duplicates.
technology databases

  1. True

  2. False

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Correct Option: A

Bitmap index is suitable for the tables having huge and repeatative(duplicates) data.
technology databases

  1. True

  2. False

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Correct Option: A

SPLIT function is available in SQL server 2005?
technology databases

  1. True

  2. False

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Correct Option: B

DDL means?

technology databases

  1. Data Dynamic Link

  2. Data Description Language

  3. Data Definition Language

  4. Data Definition Link

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Correct Option: C