tommy

Which of the following statements is true regarding Transactions in PostgreSQL?

• Transactions are automatically committed after each SQL statement execution

• Transactions cannot be rolled back once committed.

• Transactions provide a way to group multiple SQL statements into a single, logical

  unit of work.

• Transactions are always isolated from each other to prevent concurrent access

This type of indexes cannot store multiple rows with the same values

• UNIQUE

• MULTICULUMN

• FUNCTIONAL-BASED

• LIST

Choose correct statement

• The BETWEEN operator cannot be used within a subquery however, the BETWEEN can be used with the subquery

• The BETWEEN operator cannot be used with a subquery and within the subquery

• The BETWEEN operator cannot be used with a subquery, however, the BETWEEN can be used within the subquery

• The BETWEEN operator can be used with a subquery and within the subquery

Choose correct statement

• NONE OF THEM

• Subqueries that return more than one row can be used with ANY operator

• Subqueries that retum more than one row can be used with IN operator

• both of them

Which set operator returns rows in first query not present in output of the second query?

• INTERSEC

• EXCEPT

• UNION

• UNION ALL

Which of the following database events can activate a Trigger in PostgresQL?

• Schema changes such as table creation or alteration

• COMMIT and ROLLBACK transactions

• SELECT statements

• INSERT, UPDATE, and DELETE operations

Which dause is often used to generate the subtotals and the grand total for reports?

• ROLLUP

• ALL

• EXCEPT

• CUBE

What will be an output of the following SQU query?

SELECT fight_ID, LEAD(arrival airport_id) OVER (PARTITION BY depture_airport_id ORDER BY actual _departure) AS result FROM fights

• Unique row number to each flight sorted by departure time within each airline

• The time difference in minutes between consecutive flights for each airline

• First Right of the day for esch airline

• Next destination airport for each flight departing from a specific airport

Choose correct statement

• The LAGO function has the ability to access data from the previous row

• The LAGO function has the ability to access data from the next row

• LAGO and LEADO cannot access data from the previous row

• The LEADO function can access data from the previous row

Which clause is mandatory after the following SQL. query?

SELECT customer_id, SUM (amount) FROM payment ....

• ORDER BY (customer id)

• GROUP BY SUM (amount)

• GROUP BY (customer id)

• ORDER BY SUM (amount)