How to get Top 10 Rows from a Table in SQLite: A Beginner’s Guide 🔗

What You’ll Learn 🔗

In this tutorial, you’ll learn how to retrieve the top 10 rows from a table in SQLite using basic SQL concepts. By the end of this tutorial, you’ll understand how to use the ORDER BY and LIMIT clauses to get the top rows from a sorted result set.

SQL Basics Refresher 🔗

Before we dive into the tutorial, let’s cover some essential SQL concepts:

• SELECT: Retrieves data from a database table.
• FROM: Specifies the table(s) to retrieve data from.
• ORDER BY: Sorts the retrieved data in ascending or descending order.
• LIMIT: Limits the number of rows returned in the result set.

Overview of the Dataset and Tutorial Goal 🔗

We’ll be working with a sample students table that contains information about students, including their names, ages, and scores. Our goal is to learn how to retrieve the top 10 students based on their scores using SQLite.

Retrieving Top 10 Rows: Syntax and Example 🔗

The basic syntax to retrieve the top 10 rows from a table in SQLite is:

SELECT *
FROM table_name
ORDER BY column_name [ASC | DESC]
LIMIT 10;

Here’s a breakdown of the syntax:

• SELECT * selects all columns from the table.
• FROM table_name specifies the table to retrieve data from.
• ORDER BY column_name [ASC | DESC] sorts the data in ascending (ASC) or descending (DESC) order based on the specified column.
• LIMIT 10 limits the number of rows returned to 10.

Let’s create a sample students table with the following data:

CREATE TABLE students (
  id INTEGER PRIMARY KEY,
  name TEXT,
  age INTEGER,
  score REAL
);

INSERT INTO students (name, age, score)
VALUES
    ('John', 18, 85.0),
    ('Emily', 19, 90.0),
    ('Michael', 18, 78.0),
    ('Sarah', 19, 92.0),
    ('William', 18, 88.0),
    ('Olivia', 19, 95.0),
    ('David', 18, 80.0),
    ('Jessica', 19, 91.0),
    ('James', 18, 82.0),
    ('Hannah', 19, 96.0),
    ('Robert', 18, 84.0),
    ('Sophia', 18, 87.0),
    ('Daniel', 19, 93.0),
    ('Ava', 18, 89.0),
    ('Lucas', 19, 94.0),
    ('Isabella', 18, 83.0);

Now, let’s retrieve the top 10 students based on their scores:

SELECT *
FROM students
ORDER BY score DESC
LIMIT 10;

This will return the top 10 students with the highest scores.

Understanding ORDER BY and LIMIT 🔗

The ORDER BY clause sorts the data in ascending or descending order based on the specified column. When used with the LIMIT clause, it returns the top or bottom n rows from the sorted result set.

For example, if you want to retrieve the top 10 students with the highest scores, you would use ORDER BY score DESC to sort the scores in descending order and then LIMIT 10 to return the top 10 rows.

Best Practices and Advanced Examples 🔗

When using ORDER BY and LIMIT clauses, it’s essential to consider the following best practices:

• Indexing: Make sure to index the columns used in the ORDER BY clause to improve query performance.
• Avoid selecting unnecessary columns: Only select the columns you need to reduce the amount of data transferred and improve query performance.

Exercises and Solutions 🔗

Try the following exercises to reinforce your understanding of the concepts learned in this tutorial:

1. Retrieve the top 5 students with the lowest scores.

-- Your answer here

2. Retrieve the top 10 students with the highest ages.

-- Your answer here

3. Retrieve the top 5 students with the highest scores, but only include the name and score columns.

-- Your answer here

Solutions

1. Retrieve the top 5 students with the lowest scores.

SELECT *
FROM students
ORDER BY score ASC
LIMIT 5;

2. Retrieve the top 10 students with the highest ages.

SELECT *
FROM students
ORDER BY age DESC
LIMIT 10;

3. Retrieve the top 5 students with the highest scores, but only include the name and score columns.

SELECT name, score
FROM students
ORDER BY score DESC
LIMIT 5;

Summary and Key Takeaways 🔗

Congratulations! You now know how to retrieve the top 10 rows from a table in SQLite. Remember to practice and reinforce your understanding of the concepts learned in this tutorial.

Key takeaways:

• Use the ORDER BY clause to sort data in ascending or descending order.
• Use the LIMIT clause to limit the number of rows returned in the result set.
• Combine ORDER BY and LIMIT to retrieve the top or bottom n rows from a sorted result set.
• Experiment with advanced scenarios and examples to improve your SQL skills.