What potential issue should be considered when using correlated subqueries?
They cannot be used with aggregate functions.
They can lead to performance issues if not used carefully.
They require the use of the JOIN clause.
They cannot return more than one column.
Which SQL clause is used to sort the result set?
SORT BY
ORDER
SORT
ORDER BY
Which aggregate function would you use to find the highest value in a column?
SUM()
MAX()
MIN()
AVG()
Which comparison operator means 'not equal to' in SQL?
=
<>
<
!=
What is the purpose of the COUNT() function in SQL?
COUNT()
Calculates the sum of values in a column
Returns the average value of a column
Finds the minimum value in a column
Returns the number of rows in a table
Which type of subquery is used to check if a value exists in a list of values returned by another query?
Correlated Subquery
Nested Subquery
IN Subquery
EXISTS Subquery
What is the primary clause used to retrieve data from a table in SQL?
RETRIEVE
SELECT
GET
FETCH
What is the purpose of the 'OR' operator in a SQL WHERE clause?
It selects rows where at least one condition is true.
It limits the number of rows returned.
It selects rows where both conditions are true.
It negates a condition.
You want to find customers who have placed orders in the last month. You have two tables: 'Customers' and 'Orders'. Which subquery type would be most efficient to achieve this?
Any of the above would be equally efficient.
What does SQL stand for?
Structured Query Language
Standard Query Logic
Simple Query Language
System Query Language