CREATE TABLE sessions (
   userid     MEDIUMINT UNSIGNED NOT NULL,
   sessid     MEDIUMINT UNSIGNED NOT NULL,
   PRIMARY KEY (userid, sessid),
   auth       CHAR(10) NOT NULL,
   exptype    ENUM('short','long') NOT NULL,  # browser closed OR "infinite"
   timecreate INT UNSIGNED NOT NULL,
   timeexpire INT UNSIGNED NOT NULL,
   ipfixed    CHAR(15)  # IF NULL, NOT fixed at IP.
)