[db] add triggers and change value inserts

db/pyheatpump.sql

 	type CHAR(1) NOT NULL,
 	address INT NOT NULL,
 	unit VARCHAR(5) NULL,
-	last_update DATE NULL,
+	last_update INT NULL,
 
 
 	FOREIGN KEY (type) REFERENCES var_type(slabel)
 CREATE TABLE IF NOT EXISTS var_value (
 	type CHAR(1) NOT NULL,
 	address INT NOT NULL,
-	time DATE DEFAULT CURRENT_TIMESTAMP,
+	time INT DEFAULT CURRENT_TIMESTAMP,
 	value INT NOT NULL,
 
 	FOREIGN KEY (type) REFERENCES variable(type)
 );
 
 INSERT INTO var_type (slabel, label, type, start_address, end_address) VALUES (
-	'A', 'Analog', 'float', 1, 500);
+	'A', 'Analog', 'float', 1, (1 + 500));
 INSERT INTO var_type (slabel, label, type, start_address, end_address) VALUES (
-	'I', 'Integer', 'int', 5002, 6252);
+	'I', 'Integer', 'int', 5002, (5002 + 500));
 INSERT INTO var_type (slabel, label, type, start_address, end_address) VALUES (
-	'D', 'Digital', 'boolean', 1, 1000);
+	'D', 'Digital', 'boolean', 1, (1 + 1000));
+
+CREATE TRIGGER variable_insert BEFORE INSERT ON var_value
+FOR EACH ROW
+WHEN
+	NOT EXISTS (
+		SELECT MAX(time) FROM var_value
+		WHERE
+			NEW.type = type
+			AND
+			NEW.address = address
+			AND
+			NEW.value = value
+	)
+BEGIN
+	INSERT INTO var_value
+	(type, address, value)
+	VALUES (NEW.type, NEW.address, NEW.value);
+END;
+
+CREATE TRIGGER variable_last_update AFTER INSERT ON var_value
+FOR EACH ROW
+BEGIN
+	UPDATE variable
+	SET last_update = NEW.time
+	WHERE
+		type = NEW.type
+		AND
+		address = NEW.address;
+END;

db/test_variable_values.sql

-INSERT INTO var_value (type, address, value) VALUES
-('A', 10, 42),
-('A', 11, 24),
-('A', 10, 20),
-('A', 10, 0),
-('I', 5010, 42),
-('I', 5011, 24),
-('I', 5010, 20),
-('I', 5010, 0),
-('D', 10, 1),
-('D', 11, 1),
-('D', 10, 1),
-('D', 10, 0);
+INSERT INTO var_value (type, address, value, time) VALUES
+('A', 10, 42, strftime('%s', 'now')),
+('A', 11, 24, strftime('%s', datetime('now', '-1 hours'))),
+('A', 10, 20, strftime('%s', datetime('now', '-1 days'))),
+('A', 10, 0, strftime('%s', datetime('now', '-2 days'))),
+('I', 5010, 42, strftime('%s',  datetime('now'))),
+('I', 5011, 24, strftime('%s',  datetime('now'))),
+('I', 5010, 20, strftime('%s',  datetime('now', '-1 hours'))),
+('I', 5010, 0, strftime('%s',  datetime('now', '-2 days'))),
+('D', 10, 1, strftime('%s',  datetime('now'))),
+('D', 11, 1, strftime('%s',  datetime('now'))),
+('D', 10, 1, strftime('%s',  datetime('now', '-1 days'))),
+('D', 10, 0, strftime('%s',  datetime('now', '-2 days')));