There's a mistake on the CONFIGURE page on http://modauthmysql.sourceforge.net/CONFIGURE
In "EXAMPLE of Basic Authentication" you have:
CREATE TABLE user_info (
user_name CHAR(30) NOT NULL,
user_passwd CHAR(20) NOT NULL,
user_group CHAR(10),
[ any other fields if needed ]
PRIMARY KEY (user)
)
While I think it should be:
CREATE TABLE user_info (
user_name CHAR(30) NOT NULL,
user_passwd CHAR(20) NOT NULL,
user_group CHAR(10),
[ any other fields if needed ]
PRIMARY KEY (user_name)
)