CREATE TABLE history (TIMESTAMP TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP, DEVICE varchar(64), TYPE varchar(64), EVENT varchar(512), READING varchar(64), VALUE varchar(128), UNIT varchar(32));
CREATE TABLE current (TIMESTAMP TIMESTAMP, DEVICE varchar(64), TYPE varchar(64), EVENT varchar(512), READING varchar(64), VALUE varchar(128), UNIT varchar(32));
CREATE INDEX Search_Idx ON `history` (DEVICE, READING, TIMESTAMP);