How to compare a new value to last value in the table - mysql

Question

I am trying to create a trigger in MySQL database. I have a table (myData) with 3 columns. Date, Values, and Status. What I am trying to achieve is, when a new value comes, if it is higher than the last value, It should insert 1 in the Status column. If it is less than the last value, It should insert 0 in the status column. I couldn't find a logic to do it. Any suggestions, please?
BEGIN
IF new.Values > // what should be here?
THEN
INSERT INTO //
END

Answer 1

Instead consider the following:
SELECT * FROM my_table;
+----+-------+
| id | value |
+----+-------+
| 1 | 2 |
| 2 | 12 |
| 3 | 13 |
| 4 | 9 |
| 5 | 7 |
| 6 | 6 |
| 7 | 8 |
| 8 | 3 |
| 9 | 10 |
| 10 | 1 |
| 11 | 18 |
| 12 | 4 |
| 13 | 6 |
| 14 | 0 |
| 15 | 2 |
| 16 | 8 |
| 17 | 14 |
| 18 | 7 |
| 19 | 15 |
| 20 | 11 |
| 21 | 12 |
| 22 | 7 |
| 23 | 20 |
| 24 | 17 |
| 25 | 8 |
| 26 | 6 |
| 27 | 6 |
| 28 | 12 |
| 29 | 3 |
| 30 | 18 |
| 31 | 1 |
| 32 | 12 |
+----+-------+
SELECT a.*
, b.value >= a.value n
FROM my_table a
LEFT
JOIN
( SELECT x.*
, MIN(y.id) next
FROM my_table x
LEFT
JOIN my_table y
ON y.id > x.id
GROUP
BY x.id
) b
ON b.next = a.id;
+----+-------+------+
| id | value | n |
+----+-------+------+
| 1 | 2 | NULL |
| 2 | 12 | 0 |
| 3 | 13 | 0 |
| 4 | 9 | 1 |
| 5 | 7 | 1 |
| 6 | 6 | 1 |
| 7 | 8 | 0 |
| 8 | 3 | 1 |
| 9 | 10 | 0 |
| 10 | 1 | 1 |
| 11 | 18 | 0 |
| 12 | 4 | 1 |
| 13 | 6 | 0 |
| 14 | 0 | 1 |
| 15 | 2 | 0 |
| 16 | 8 | 0 |
| 17 | 14 | 0 |
| 18 | 7 | 1 |
| 19 | 15 | 0 |
| 20 | 11 | 1 |
| 21 | 12 | 0 |
| 22 | 7 | 1 |
| 23 | 20 | 0 |
| 24 | 17 | 1 |
| 25 | 8 | 1 |
| 26 | 6 | 1 |
| 27 | 6 | 1 |
| 28 | 12 | 0 |
| 29 | 3 | 1 |
| 30 | 18 | 0 |
| 31 | 1 | 1 |
| 32 | 12 | 0 |
+----+-------+------+
If all you want is the rows where n=1, then the query is actually even simpler...
SELECT a.*
FROM my_table a
JOIN
( SELECT x.*
, MIN(y.id) next
FROM my_table x
LEFT
JOIN my_table y
ON y.id > x.id
GROUP
BY x.id
) b
ON b.next = a.id
AND b.value >= a.value;
+----+-------+
| id | value |
+----+-------+
| 4 | 9 |
| 5 | 7 |
| 6 | 6 |
| 8 | 3 |
| 10 | 1 |
| 12 | 4 |
| 14 | 0 |
| 18 | 7 |
| 20 | 11 |
| 22 | 7 |
| 24 | 17 |
| 25 | 8 |
| 26 | 6 |
| 27 | 6 |
| 29 | 3 |
| 31 | 1 |
+----+-------+