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.