W3. SQL Select Top

Question 1

Q: What does the SQL SELECT TOP clause do?

Answer 1

A: It specifies the number of records to return from a query, often to improve performance on large tables.

Question 2

Q: Write an example query to select the first 3 records from the “Customers” table using SELECT TOP.

Answer 2

SELECT TOP 3 * FROM Customers;

Question 3

Q: Which SQL clause does MySQL use instead of SELECT TOP?

Answer 3

LIMIT

Question 4

Q: Write a MySQL query to select the first 3 records from the “Customers” table.

Answer 4

SELECT * FROM Customers 
LIMIT 3;

Question 5

Q: What clause does Oracle use to limit records?

Answer 5

A: FETCH FIRST n ROWS ONLY or ROWNUM

Question 6

Q: Write an Oracle query to select the first 3 records from the “Customers” table.

Answer 6

SELECT * FROM Customers 
FETCH FIRST 3 ROWS ONLY;

Question 7

Q: How do you select a percentage of records using SELECT TOP?

Answer 7

A: Add PERCENT after the number, e.g.,
SELECT TOP 50 PERCENT * FROM Customers;

Question 8

Q: Write a SQL Server query to select the first 50% of records from the “Customers” table.

Answer 8

SELECT TOP 50 PERCENT * FROM Customers;

Question 9

Q: How can you limit records with a condition (e.g., customers from Germany) using SELECT TOP?

Answer 9

SELECT TOP 3 * FROM Customers 
WHERE Country = 'Germany';

Question 10

Q: Write a MySQL query to select the first 3 customers from Germany.

Answer 10

SELECT * FROM Customers 
WHERE Country = 'Germany' 
LIMIT 3;

Question 11

Q: How do you sort and limit the result set using ORDER BY with SELECT TOP?

Answer 11

A: Add ORDER BY after specifying TOP, e.g.,
SELECT TOP 3 * FROM Customers ORDER BY CustomerName DESC;

Question 12

Q: Write a query to select the top 3 customers sorted in reverse alphabetical order by CustomerName (for MySQL).

Answer 12

SELECT * FROM Customers 
ORDER BY CustomerName DESC 
LIMIT 3;

Question 13

Q: Write an Oracle query to fetch the top 3 customers sorted in reverse alphabetical order by CustomerName.

Answer 13

SELECT * FROM Customers 
ORDER BY CustomerName DESC 
FETCH FIRST 3 ROWS ONLY;