What is SQLite? An overview of the relational database solution

SQLite is a lean software library or database that is integrated into numerous applications. One of its distinguishing features is its lack of a client-server structure. SQLite alternatives include MySQL, MongoDB and PostgreSQL.

What is SQLite?

SQLite is the most widely used database system in the world. Originally designed by D. Richard Hipp in 2000 for the US Army, the software is now available in the public domain and thus copyright-free. The name ‘SQLite’ is comprised of ‘SQL’, which is short for ‘Structured Query Language’, and ‘lite’, a colloquial term used here to indicate that the database is a lighter and less memory-intensive version.

Its name alludes to the fact that, unlike other common databases, the relational database SQLite doesn’t require additional server software. Additionally, the lightweight system has a small size of only a few hundred kilobytes and stores an entire database in one file.

SQLite is written in the web programming language C and is used in numerous operating systems and programs, including Android, iOS and Windows Phone as well as Google Chrome, Mozilla Firefox and Safari SQLite. It’s also used in the instant messaging app Skype. The respective data is stored in tables in the program library and can be retrieved column by column. Integration with other programs is simple and can be done via the C interface or an interface such as Ruby, PHP or Python.

With SQLite3 Python, the popular programming language now has an integration module for SQLite. There’s also no need to install or configure the open-source database system.

How does SQLite work?

There’s no steep learning curve with SQLite. It can be easily integrated into an application without the use of additional server software. The app then automatically receives comprehensive database functions. All tables, references and links are accommodated in a single, space-saving file. Optionally, the file can also be stored in the main memory.

This means that using a file in different systems is simple, in part because data can be stored within a table. These are converted only if necessary, so that changing between systems with a different byte order is possible.

As a relational database management system, it uses a two-key principle to identify entries in a table and to link different tables. A primary key and a foreign key are used for this purpose.

• Primary key: this is a unique value that can be assigned to a specific row in the table.
• Foreign key: this is used to link multiple tables together.

These references provide a much leaner structure and make it easier to work with SQLite compared to other databases. These attributes have also contributed to the global success of the database system.

Which data types are possible with SQLite?

With SQLite, data can be stored in different formats. This also means that conversion isn’t necessarily required for further processing across systems. The possible data types that can be saved and stored are:

• INTEGER: this encompasses all integer values.
• REAL: this includes approximated representations of a real number as a floating point. -TEXT: this data type contains all plain text content.
• BLOB: this term stands for binary large object and refers to data in a binary value format, such as thumbnails or configuration files in XML.
• NULL: this allows for null values to be mapped in SQLite

This means all common data types can be stored in SQLite.

How is data secured in SQLite?

There are two ways to ensure the consistency of a database in SQLite. They are:

• Rollback Journal: this method automatically creates a temporary journal of all changes and stores it under the name of the respective database with the extension ‘-journal’. If there are problems with the database or individual files, a rollback can be carried out and an earlier status is restored.
• Write Ahead Log (WAL): with a Write Ahead Log, all changes are saved in a log file. When the database is closed, the data is inserted into the database. Alternatively, you can save changes manually with a commit command. At the same time, an index is created in the shared memory file (SHM).

What are the advantages of SQLite?

SQLite has several advantages, which has earned it a good reputation among both private users and developers of commercial applications. The following aspects are what make the relational system such a popular choice:

Scope

Low memory requirements are a major advantage of the database system. At just a few hundred kilobytes, the library takes up little space. This positively affects performance speed. SQLite lives up to its name and proves to be a strong solution for large and small applications alike.

No need for additional software

SQLite doesn’t require server software and can easily be integrated. Additional programs or external packages aren’t required. The provided server performance is clearly displayed and easy to manage.

Versatility

SQLite supports most SQL language commands and is compatible with most popular data stores. That’s why the library is used in numerous apps such as Facebook and WhatsApp as well as in all major browsers, commercial programs and client operating systems. Because the exchange between two different systems is simplified, numerous developers rely on the lean solution as a substructure for their software.

Portability

The aspects mentioned above also tie in with the fact that SQLite files are easy to back up and transport. Since SQLite files are independent of server programs and it’s not necessary to configure the database, it’s possible to use SQLite on different systems without any issues arising.

Reliability

Unified data access, low resource consumption and independence from a server-client structure make SQLite a secure option. Memory errors or problems caused by insufficient RAM are less of an issue with this database.

Public domain

SQLite is available license-free. However, there are fees for customer support and some add-ons.

What are the disadvantages of SQLite?

SQLite has a few disadvantages you should be aware of and take into consideration when thinking about using the database system. They include:

User restriction

SQLite doesn’t have an option for multiple user accounts, which removes the possibility to connect multiple clients via their accounts. This distinguishes the solution from other providers.

Increasing space requirements

Although SQLite is a lean solution, demand increases the larger the database becomes. This can negatively affect performance.

Flexibility

While its independence from external server structures makes SQLite a flexible solution, data queries from the client aren’t possible. In addition, multiple connections cannot be processed at the same time, which can cause delays.

What alternatives to the database library are there?

Numerous SQLite alternatives are available. In addition to the document-oriented NoSQL solution MongoDB and the relational PostgreSQL, MySQL is another widely used alternative that is very user-friendly. It is partly proprietary and partly open source. Learn how to use this database system in our MySQL tutorial.