Databases & SQL worksheet with answers

GRANT and REVOKE belong to which part of SQL?

1. AData Manipulation Language (DML)
2. BData Definition Language (DDL)
3. CData Control Language (DCL)
4. DData Query Language (DQL)

Which statement deletes a whole table, including its structure?

1. AREMOVE TABLE
2. BTRUNCATE ROWS
3. CDELETE FROM
4. DDROP TABLE

Which rows does WHERE price BETWEEN 10 AND 20 select?

1. ARows with price equal to 10 or 20 only
2. BRows with price outside the range 10 to 20
3. CRows with price from 10 to 20, including 10 and 20
4. DRows with price above 10 and below 20, excluding 10 and 20

Which statement about HAVING is correct?

1. AIt must come before WHERE in the SELECT statement
2. BIt cannot be used with GROUP BY
3. CIt sorts the results
4. DIt can use aggregate functions to filter groups

What does ROLLBACK TO SAVEPOINT s1 do?

1. AUndoes the changes made after savepoint s1, keeping the transaction open
2. BDeletes the savepoint and all tables changed since then
3. CEnds the transaction and commits everything
4. DUndoes the whole transaction from the beginning

What is a dirty read?

1. AReading the same row twice and getting the same value
2. BReading data without a WHERE clause
3. CReading data from a corrupted disk
4. DReading data written by another transaction that has not yet committed

What is a phantom read?

1. AA repeated query returns new rows inserted by another committed transaction
2. BReading data that was never written
3. CReading uncommitted changes
4. DA query that returns no rows

What does the write-ahead logging (WAL) rule require?

1. AA change's log record must reach stable storage before the changed data page does
2. BEvery query must be logged before it is parsed
3. CData pages must be written before the log
4. DThe log is written only after a crash