DbSchema | How to Implement LIMIT Clause in SQLite?

Sqlite • 05-Jun-2023

by Malik Umair Sajjad

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Introduction
Prerequisites
What is the LIMIT Clause?
Advantages of Using the LIMIT Clause
Limitations and Restrictions of Using the LIMIT Clause
Implementing the LIMIT Clause in sqlite3
Implementing the LIMIT Clause in DbSchema
Conclusion
References

Introduction

SQLite is a software library that provides a relational database management system. In this article, we will explore the LIMIT clause in SQLite, how to implement it using the sqlite3 library and DbSchema, and also discuss the advantages, limitations, and potential restrictions.

Prerequisites

SQLite3 installed on your local machine.
DbSchema installed on your local machine.
Basic understanding of SQL and database concepts.

For installation and establishing connection you can read our article SQLite-How to create a database?

What is the LIMIT Clause?

The LIMIT clause in SQLite is used to constrain the number of rows returned by the SELECT statement. This is especially useful when dealing with large databases where returning all data could be costly in terms of performance.

Here is a general syntax:

SELECT column1, column2, ...
FROM table_name
LIMIT number;

Advantages of Using the LIMIT Clause

Performance: When dealing with large databases, LIMIT can significantly reduce the number of rows processed, improving query performance.
Paginated Results: It’s useful for fetching paginated results by using it with the OFFSET keyword.

Limitations and Restrictions of Using the LIMIT Clause

Ordering: The LIMIT clause does not guarantee the order of the rows returned. If specific ordering is required, it’s best to use it with the ORDER BY clause.
Portability: Not all database systems support the LIMIT clause, which can lead to portability issues.

Implementing the LIMIT Clause in sqlite3

Step 1: Start SQLite Interactive Shell

Open your terminal (Command Prompt on Windows, Terminal app on macOS or Linux) and type the following command to start the SQLite interactive shell.

sqlite3

This will open the SQLite command line interface.

Step 2: Create a Database (If not exists)

If you don’t have a database to work on, you can create a new one. Use the following command to create a new database named SampleDB.

sqlite3 SampleDB.db

To know more about creating a database you can read our article SQLite-How to create a database?

Step 3: Create a New Table

We’ll need a table to implement LIMIT Clause. If you don’t already have a table, you can create one using the CREATE TABLE command. Let’s create a table named orders with columns id, product, and quantity..

CREATE TABLE orders(
   id INT PRIMARY KEY,
   product TEXT NOT NULL,
   quantity INT NOT NULL
);

To know more about creating a table you can read our article SQLite-How to create a Table?

Step 4: Inserting Data into the Table

Next, let’s insert some data into the ‘orders’ table.

INSERT INTO orders (id, product, quantity) VALUES 
   (1, 'Apples', 5),
   (2, 'Oranges', 7),
   (3, 'Bananas', 8),
   (4, 'Grapes', 10),
   (5, 'Pears', 6);

orders table:

id	_product_	*quantity*
1	Apples	5
2	Oranges	7
3	Bananas	8
4	Grapes	10
5	Pears	6

Step 5: Using the LIMIT Clause

Now, we can use the LIMIT clause to limit the number of rows returned by our SELECT statement. Let’s retrieve only the first three records:

SELECT * FROM orders LIMIT 3;

Result After Execution:

The output will be:

_id_	*product*	*quantity*
1	Apples	5
2	Oranges	7
3	Bananas	8

And that’s it! You have successfully used the LIMIT clause in sqlite3.
You can exit the sqlite3 interface by typing .exit and hitting enter.

Remember, SQLite does not guarantee an order for the rows returned. If you want to enforce an order, use the ORDER BY clause in conjunction with LIMIT.

Implementing the LIMIT Clause in DbSchema

Step 1: Install and Open DbSchema

Before we start, make sure DbSchema is installed on your computer. You can download it from the official DbSchema website.

Once installed, open the DbSchema application.

Step 2: Connect to Your SQLite Database

To connect to your SQLite database, click on the “Connect” button from the toolbar.

In the connection dialog box, choose SQLite as the database type.
Specify the path to your SQLite database file (for example, SampleDB.db that we created earlier).
Click on “Test Connection” to make sure everything is set up correctly, and then click “Connect”.

Step 3: Open SQL Editor

In the DbSchema interface, navigate to SQL Editor. You can find it in the top menu under SQL, or you can press the SQL icon in the toolbar.

Step 4: Write and Run Your Query

In the SQL Editor, you can write your SQL query with the LIMIT clause. To retrieve the first three records from the orders table, the SQL statement would look like this:

SELECT * FROM orders LIMIT 3;

To execute the query, press the Execute SQL (Play) button or use the shortcut (F5 or Ctrl+Enter).

Step 5: View the Results

The results of your query will be displayed in the data output pane below the SQL Editor. You should see the first three rows from the orders table.

And there you have it! You’ve successfully implemented the LIMIT clause using DbSchema.

Remember, you can combine the LIMIT clause with the ORDER BY clause if you want to retrieve rows in a specific order.

Visually Manage SQLite using DbSchema

DbSchema is a SQLite client and visual designer. DbSchema has a free Community Edition, which can be downloaded here.

Key Features of DbSchema:

Following are the key features of DbSchema which distinguish it from other database GUI tools.

Conclusion

The LIMIT clause is a simple yet powerful feature in SQL that lets you control the amount of data retrieved from the database. Whether you’re using sqlite3 or DbSchema, the syntax and usage remain largely the same. However, remember the limitations and always consider the performance and ordering of your results.