Harvard Mathematics Department : Computing: SQLite

SQLite SQLite is a database, which implements a large subset of the SQL92 standard. It is simple, small, fast and reliable. Reliability is a consequence of simplicity. SQLite is a typeless database system. It is in the public domain. Everything about a database is stored in a single file. Databse files can so freely be shared between machines. A database can be up to 2 terabytes in size.

The Perl module DBD::SQLite, that is not an interface to SQLite, but rather includes the entire SQLite database engine in itself.
PHP 5 comes with SQLite included.
Mac OS X tiger has SQLite built in (just type sqlite3 on the commandline).
Apple Mail, the RSS manager or Apple's Aperture software stores image information as an SQLite database.
Firefox 2 will use sqlite to manage bookmarks etc.
There Python module called y_serial which provides a very reliable NoSQL interface for SQLite.

sqlite3 example1.sqlt

at the sqlite> command prompt type:

create table table1(x varchar(10), y smallint); 
insert into table1 values('hello!',  10);
insert into table1 values('goodbye', 20);
select * from table1;
.quit

When you access the database again, this information can be accessed again:

sqlite example1.sqlt
select * from table1;

Situations where SQLite is good to use

SLite works well for websites with fewer than 100'000 hits/day.
SQLite database require no administration. SQLite is a good choice for devices or services that must work unattended and without human support. SQLite is a good fit for use in cell phones or PDAs.
It can be used as a replacement for ad hoc disk files.
It is well suited for internal or temporary databases
Experienced SQL users can employ the command-line sqlite program to analyze miscellaneous datasets.

Situations, where other RDBMS may work better

If many client programs accesse a common database over a
If you have a high-volume Websites
If you use a very large dataset larger than a few dozen GB of data.
SQLite uses reader/writer locks on the entire database file. This could be a problem if an application requires high concurrency.

Links:

Simplicity, Clarity, Generality B.W. Kernighan, R. Pike, in "The Practice of Programming".