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A small MySQL client library for chicken-scheme. This egg makes it possible to execute an SQL query on a MySQL database.
A. Carl Douglas
Requires MySQL database system development components, libmysqlclient and mysql_config.
The mysql_config program needs to be in the $PATH so the linker can find the native MySQL libraries.
On a Linux machine, consider trying:
apt-get install libmysqlclient-dev
API[procedure] (make-mysql-connection hostname username password schema)
This procedure will return a procedure that contains a closed off MySQL connection and can execute a query when called.
Here is a trivial example:
(use mysql-client) (define mysql (make-mysql-connection "localhost" "root" #f "information_schema")) (define fetch (mysql "SELECT * FROM schemata")) (display (fetch)) (newline)
Here is an example that will use the mysql_real_escape_string MySQL function to safely escape parameters in the query string using a placeholder syntax. In this case, the first argument is a string containing an SQL query, and the second argument will be an association list where the key represents the placeholder symbol in the query.
(use mysql-client) (define mysql (make-mysql-connection "localhost" "username" "secret" "database")) (define fetch (mysql "SELECT * FROM t1 WHERE c1 = '$1' OR c2 = '$2'" '(($1 . "value 1';' ;")($2 . "value 2'; drop database; ")))) (display (fetch)) (newline)
Other placeholder conventions are possible as well, as the keys from the association list are matched in the query.
(define fetch (mysql "SELECT * FROM t WHERE created_on < '?to' AND created_on > '?from' LIMIT 5" '((?from . "2012-04-01 00:00")(?to . "2012-04-01 24:00"))))
For power users, to access directly the MySQL connection object pointer, pass a procedure to the MySQL client closure.
(use mysql-client) (define mysql (make-mysql-connection "localhost" "username" "secret" "database")) (define fetch (mysql (lambda(c)(printf "~S ~%" c)))) (display (fetch)) (newline)
Copyright (C) 2012, A. Carl Douglas All rights reserved.
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- 0.4 Initial publication