SQLite

<h1 align="center">SQLite Source Repository</h1>

This repository contains the complete source code for the SQLite database
engine.  Some test scripts are also include.  However, many other test scripts
and most of the documentation are managed separately.

If you are reading this on a Git mirror someplace, you are doing it wrong.
The [official repository](https://www.sqlite.org/src/) is better.  Go there
now.

## Obtaining The Code

to the "sqlite3.dll" command line above.  When debugging into the SQLite
code, adding the "DEBUG=1" argument to one of the above command lines is
recommended.

SQLite does not require [Tcl](http://www.tcl.tk/) to run, but a Tcl installation
is required by the makefiles (including those for MSVC).  SQLite contains
a lot of generated code and Tcl is used to do much of that code generation.
The makefiles also require AWK.

## Source Code Tour

Most of the core source files are in the **src/** subdirectory.  The
**src/** folder also contains files used to build the "testfixture" test
harness. The names of the source files used by "testfixture" all begin
with "test".
The **src/** also contains the "shell.c" file
which is the main program for the "sqlite3.exe"
[command-line shell](https://sqlite.org/cli.html) and
the "tclsqlite.c" file which implements the
[TCL bindings](https://sqlite.org/tclsqlite.html) for SQLite.
(Historical note:  SQLite began as a Tcl
extension and only later escaped to the wild as an independent library.)

Test scripts and programs are found in the **test/** subdirectory.
Addtional test code is found in other source repositories.
See [How SQLite Is Tested](http://www.sqlite.org/testing.html) for
additional information.

the src/parse.y file.  The conversion of "parse.y" into "parse.c" is done
by the [lemon](./doc/lemon.html) LALR(1) parser generator.  The source code
for lemon is at tool/lemon.c.  Lemon uses the tool/lempar.c file as a
template for generating its parser.

Lemon also generates the **parse.h** header file, at the same time it
generates parse.c. But the parse.h header file is
modified further (to add additional symbols) using the ./addopcodes.awk
AWK script.

The **opcodes.h** header file contains macros that define the numbers
corresponding to opcodes in the "VDBE" virtual machine.  The opcodes.h
file is generated by the scanning the src/vdbe.c source file.  The
AWK script at ./mkopcodeh.awk does this scan and generates opcodes.h.
A second AWK script, ./mkopcodec.awk, then scans opcodes.h to generate
the **opcodes.c** source file, which contains a reverse mapping from
opcode-number to opcode-name that is used for EXPLAIN output.

The **keywordhash.h** header file contains the definition of a hash table
that maps SQL language keywords (ex: "CREATE", "SELECT", "INDEX", etc.) into
the numeric codes used by the parse.c parser.  The keywordhash.h file is
generated by a C-language program at tool mkkeywordhash.c.

  *  **tclsqlite.c** - This file implements the Tcl bindings for SQLite.  It
     is not part of the core SQLite library.  But as most of the tests in this
     repository are written in Tcl, the Tcl language bindings are important.

  *  **test*.c** - Files in the src/ folder that begin with "test" go into
     building the "testfixture.exe" program.  The testfixture.exe program is
     an enhanced TCL shell.  The testfixture.exe program runs scripts in the
     test/ folder to validate the core SQLite code.  The testfixture program
     (and some other test programs too) is build and run when you type
     "make test".

  *  **ext/misc/json1.c** - This file implements the various JSON functions
     that are build into SQLite.