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1. Introduction Every SQL database engine works in roughly the same way: It first translates the input SQL text into a "prepared statement". Then it "executes" the prepared statement to generate a result. A prepared statement is an object that represents the steps needed to accomplish the input SQL. Or, to think of it in another way, the prepared statement is the SQL statement translated into a fo
JSONB (https://sqlite.org/draft/json1.html#jsonbx) is a new binary storage format for JSON that is proposed for the next release (3.44.0) sometime toward the end of the calendar year. The advantages of using JSONB rather than RFC-8259 text JSON are: JSONB is slightly more compact, taking up about 5% or 10% less disk space, on average. JSONB is faster. The json_extract() function and the -> and ->>
The core SQLite project releases only "vanilla JS" distributions which are independent of any given developer-side toolchain. However, a community-maintained npm-based distribution of the SQLite3 WASM components can be found at @sqlite.org/sqlite-wasm. It can be installed from a command-line shell using: $ npm install @sqlite.org/sqlite-wasm An introduction for using it, including instructions for
HC-tree SQLite is sometimes used as the core of a client/server database system. While it works reliably well in such cases, the database backend module that it uses to store b-tree structures in its database file was not designed with this case in mind and can be improved upon in several ways. The HC-tree (hctree) project is an attempt to develop a new database backend that improves upon regular
WebAssembly, a.k.a. WASM, is a standard defining a low-level programming language suitable (A) as a target for cross-compilation from many other languages and (B) for running via a virtual machine in a browser. Designed with scriptability via JavaScript in mind, it provides a way to compile C code (among others) to WASM and script it via JavaScript with relatively little friction despite the vast
1. History This document was originally called a "Code of Conduct" and was created for the purpose of filling in a box on "supplier registration" forms submitted to the SQLite developers by some clients. However, we subsequently learned that "Code of Conduct" has a very specific and almost sacred meaning to some readers, a meaning to which this document does not conform [1][2][3]. Therefore this d
On a slow internet connection this may take a moment. If this message displays for "a long time", intialization may have failed and the JavaScript console may contain clues as to why.
1. Overview The default method by which SQLite implements atomic commit and rollback is a rollback journal. Beginning with version 3.7.0 (2010-07-21), a new "Write-Ahead Log" option (hereafter referred to as "WAL") is available. There are advantages and disadvantages to using WAL instead of a rollback journal. Advantages include: WAL is significantly faster in most scenarios. WAL provides more con
Althttpd is a simple webserver that has run the https://sqlite.org/ website since 2004. Althttpd strives for simplicity, security, and low resource usage. As of 2024, the althttpd instance for sqlite.org answers more than 500,000 HTTP requests per day (about 5 or 6 per second) delivering about 200GB of content per day (about 18 megabits/second) on a $40/month Linode. The load average on this machi
1. Executive Summary 200 SQL statements per webpage is excessive for client/server database engines like MySQL, PostgreSQL, or SQL Server. But with SQLite, 200 or more SQL statement per webpage is not a problem. SQLite can also do large and complex queries efficiently, just like client/server databases. But SQLite can do many smaller queries efficiently too. Application developers can use whicheve
SQLite As An Application File Format Executive Summary An SQLite database file with a defined schema often makes an excellent application file format. Here are a dozen reasons why this is so: Simplified Application Development Single-File Documents High-Level Query Language Accessible Content Cross-Platform Atomic Transactions Incremental And Continuous Updates Easily Extensible Performance Concur
The intent of the developers is to support SQLite through the year 2050. At this writing, 2050 is still 34 years in the future. Nobody knows what will happen in that time, and we cannot absolutely promise that SQLite will be viable or useful that far out. But we can promise this: we plan as if we will be supporting SQLite until 2050. That long-term outlook affects our decisions in important ways.
1. Introduction SQLite does not use the Git version control system. SQLite uses Fossil instead, which is a version control system that was specifically designed and written to support SQLite. People often wonder why SQLite does not use the Git version control system like everybody else. This article attempts to answer that question. Also, in section 3, this article provides hints to Git users abou
Note: Sections 2.0 and 3.0 of this article were added in response to comments on Hacker News and Reddit. Since its inception on 2000-05-29, SQLite has been implemented in generic C. C was and continues to be the best language for implementing a software library like SQLite. There are no plans to recode SQLite in any other programming language at this time. The reasons why C is the best language to
Overview An SQLite database is highly resistant to corruption. If an application crash, or an operating-system crash, or even a power failure occurs in the middle of a transaction, the partially written transaction should be automatically rolled back the next time the database file is accessed. The recovery process is fully automatic and does not require any action on the part of the user or the a
1. Overview The zipfile module provides read/write access to simple ZIP archives. The current implementation has the following restrictions: Does not support encryption. Does not support ZIP archives that span multiple files. Does not support zip64 extensions. The only compression algorithm supported is "deflate". Some or all of these restrictions may be removed in the future. 2. Obtaining and Com
1. Datatypes In SQLite Most SQL database engines (every SQL database engine other than SQLite, as far as we know) uses static, rigid typing. With static typing, the datatype of a value is determined by its container - the particular column in which the value is stored. SQLite uses a more general dynamic type system. In SQLite, the datatype of a value is associated with the value itself, not with i
This Is Probably Not The Project You Are Looking For SQLite4 was an experimental rewrite of SQLite that was active from 2012 through 2014. All development work on SQLite4 has ended. Lessons learned from SQLite4 have been folded into the main SQLite3 product. SQLite4 was never released. There are no plans to revive it. You should be using SQLite3. This repository preserves the history of the SQLite
Appropriate Uses For SQLite SQLite is not directly comparable to client/server SQL database engines such as MySQL, Oracle, PostgreSQL, or SQL Server since SQLite is trying to solve a different problem. Client/server SQL database engines strive to implement a shared repository of enterprise data. They emphasize scalability, concurrency, centralization, and control. SQLite strives to provide local d
1.0 Executive Summary SQLite4 is a compact, self-contained, zero-adminstration, ACID database engine in a library, just like SQLite3, but with an improved interface and file format. The run-time environment is encapsulated in an object. A greatly simplified Key/Value storage engine is used: A single large key space - not separate key spaces for each table and index as in SQLite3. Keys sort in lexi
Common Table Expressions or CTEs act like temporary views that exist only for the duration of a single SQL statement. There are two kinds of common table expressions: "ordinary" and "recursive". Ordinary common table expressions are helpful for making queries easier to understand by factoring subqueries out of the main SQL statement. Recursive common table expressions provide the ability to do hie
1. Introduction The reliability and robustness of SQLite is achieved in part by thorough and careful testing. As of version 3.42.0 (2023-05-16), the SQLite library consists of approximately 155.8 KSLOC of C code. (KSLOC means thousands of "Source Lines Of Code" or, in other words, lines of code excluding blank lines and comments.) By comparison, the project has 590 times as much test code and test
How do I create an AUTOINCREMENT field?What datatypes does SQLite support?SQLite lets me insert a string into a database column of type integer!Why doesn't SQLite allow me to use '0' and '0.0' as the primary key on two different rows of the same table?Can multiple applications or multiple instances of the same application access a single database file at the same time?Is SQLite threadsafe?How do I
Limits In SQLite "Limits" in the context of this article means sizes or quantities that can not be exceeded. We are concerned with things like the maximum number of bytes in a BLOB or the maximum number of columns in a table. SQLite was originally designed with a policy of avoiding arbitrary limits. Of course, every program that runs on a machine with finite memory and disk space has limits of som
3. ALTER TABLE RENAME COLUMN The RENAME COLUMN TO syntax changes the column-name of table table-name into new-column-name. The column name is changed both within the table definition itself and also within all indexes, triggers, and views that reference the column. If the column name change would result in a semantic ambiguity in a trigger or view, then the RENAME COLUMN fails with an error and no
C source code as an amalgamation, version 3.45.2. (SHA3-256: 8d9c553b52c7b1656a97fec7907cb00fd1419ac45104e45c76b7c2b81ffe0a9d) C source code as an amalgamation. Also includes a "configure" script and TEA makefiles for the TCL Interface. (SHA3-256: 1b02c58a711d15b50da8a1089e0f8807ebbdf3e674c714100eda9a03a69ac758)
What Is SQLite? SQLite is a C-language library that implements a small, fast, self-contained, high-reliability, full-featured, SQL database engine. SQLite is the most used database engine in the world. SQLite is built into all mobile phones and most computers and comes bundled inside countless other applications that people use every day. More Information... The SQLite file format is stable, cross
SQL As Understood By SQLite SQLite understands most of the standard SQL language. But it does omit some features while at the same time adding a few features of its own. This document attempts to describe precisely what parts of the SQL language SQLite does and does not support. A list of SQL keywords is also provided. The SQL language syntax is described by syntax diagrams. The following syntax d
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