Using Structured Query Language

---

SQL is an industry-standard database query language. All major commercial database applications, as well as free implementations such as PostgreSQL (http://www.postgresql.org/) and MySQL (http://www.mysql.org/), support SQL.

You can use SQL with qmail to store user information—much like LDAP—through the use of add-ons and patches available from the Web (http://www.qmail.org/). Although SQL is standardized, the implementations differ enough that most of these patches are specific to a particular SQL implementation.

Some of the SQL integration tools available are:

• checkpass.c, a checkpassword replacement that looks up authentication information in a PostgreSQL database (http://x.csusb.net/free/qmail/).

• sql-xpw, another checkpassword replacement for PostgreSQL (http://www.point-five.net/Qmail/).

• MySQL+QMAIL, a set of patches and a checkpassword replacement that retrieves all user information from a MySQL database (http://www.softagency.co.jp/mysql/qmail.en.html). An alternative version is also available (http://iain.cx/unix/qmail/mysql.php).

• Qmail-PGsql, a set of patches including a checkpassword replacement for use with PostgreSQL (http://www.digibel.org/qmail+pgsql/).

---