Databases & SQL worksheet with answers

Which keyword sorts the result of a query?

1. AORDER BY
2. BGROUP BY
3. CSORT
4. DARRANGE

In a LIKE pattern, what does the % wildcard stand for?

1. AAny sequence of zero or more characters
2. BExactly one character in that position of the string
3. CAny single digit
4. DThe end of the string

Statements such as CREATE, ALTER and DROP belong to which part of SQL?

1. AData Manipulation Language (DML)
2. BData Control Language (DCL)
3. CData Definition Language (DDL)
4. DTransaction Control Language (TCL)

Second normal form (2NF) removes:

1. AForeign keys
2. BAll NULL values
3. CTransitive dependencies between non-key columns via another non-key column
4. DPartial dependencies of non-key columns on part of a composite key

An employees table has a column manager_id that refers to another employee. How do you list each employee next to their manager's name?

1. AUse GROUP BY manager_id only
2. BCombine the table with itself using UNION ALL and a WHERE filter
3. CCreate a second copy of the table on disk
4. DJoin the employees table with itself using two aliases

Why does SELECT price * 2 AS double_price FROM t WHERE double_price > 10 fail in most databases?

1. AArithmetic is not allowed in the SELECT list
2. BWHERE is evaluated before the SELECT list, so the alias does not exist yet
3. CWHERE can only compare text columns
4. DAliases may not contain an underscore

There is a composite index on (last_name, first_name). Which condition can use it most effectively?

1. AWHERE first_name = 'Eva'
2. BWHERE last_name = 'Jansen'
3. CWHERE first_name LIKE '%a'
4. DWHERE UPPER(first_name) = 'EVA'

What is a phantom read?

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