Calculations involving thresholds between two tables

I have a table comment and a table price like below. The key columns in both tables are ticker_id, price_datetime and price_open. The last column threshold in table comment (which currently NULL) is something that I need to fill in with after some calculation queries (if this is achievable). comment table: +------------+---------------------+--------+---------+-----------+---------------------+------------+-----------+ | comment_id | comment_datetime | author | comment | ticker_id | price_datetime | price_open | threshold | +------------+---------------------+--------+---------+-----------+---------------------+------------+-----------+ | 1 | 2014-09-22 06:05:00 | A1 | C1 | 343 | 2014-09-22 08:00:00 | 53.25000 | | +------------+---------------------+--------+---------+-----------+---------------------+------------+-----------+ | 2 | 2014-09-22 06:39:00 | A2 | C2 | 1 | 2014-09-22 08:00:00 | 62.00000 | | +------------+---------------------+--------+---------+-----------+---------------------+------------+-----------+ | 3 | 2014-09-22 08:13:00 | A3 | C3 | 178 | 2014-09-22 08:13:00 | 5.15000 | | +------------+---------------------+--------+---------+-----------+---------------------+------------+-----------+ price table: +----------+---------------------+------------+-----------+ | price_id | price_datetime | price_open | ticker_id | +----------+---------------------+------------+-----------+ | 1 | 2014-09-22 08:01:00 | 62.00000 | 1 | +----------+---------------------+------------+-----------+ | 2 | 2014-09-22 08:02:00 | 62.00000 | 1 | +----------+---------------------+------------+-----------+ | 3 | 2014-09-22 08:03:00 | 62.00000 | 1 | +----------+---------------------+------------+-----------+ In each row of table comment, price_open will be used as "base price". - For each row of table comment - Match the ticker_id, price_datetime and price_open with table price - Then, get the +-2 days for each price_datetime (follows with the price_open) - Then, count whether any of the price.price_open within that 5 days exceeds 5%, 10% or 15% of the "base price" - Conditions: - If any of the price.price_open within that 5 days equals/exceeds 15% of the "base price", then fill in comment.threshold with "R" - If any of the price.price_open within that 5 days equals/exceeds 10% of the "base price" (but less than 15%), then fill in comment.threshold with "A" - If any of the price.price_open within that 5 days equals/exceeds 5% of the "base price" (but less than 10%), then fill in comment.threshold with "Y" - If any of the price.price_open within that 5 days is less 5%, then fill in comment.threshold with "C" - For empty values in columns comment.price_datetime and comment.price_open, we will leave it NULL as it is, thus NULL for comment.threshold as well. Is the above going to be achievable in MySQL using JOIN? I am trying to learn about JOIN right now, unfortunately it seems way too complicated to me, I have no clue about the query that I should execute as I just started learning MySQL. I've tried explaining my question in details, but if there's anything unclear, kindly let me know. Any help would be much appreciated. Thank you. **EDIT** (as requested by Verace): CREATE statements: CREATE TABLE comment ( comment_id int(11) NOT NULL AUTO_INCREMENT, comment_datetime datetime NOT NULL, author varchar(25) NOT NULL, title varchar(250) NOT NULL, comment text NOT NULL, ticker_id int(11) NOT NULL, price_datetime datetime DEFAULT NULL, price_open decimal(12,5) DEFAULT NULL, threshold varchar(10) DEFAULT NULL, PRIMARY KEY (comment_id) ) CREATE TABLE price ( price_id int(11) NOT NULL AUTO_INCREMENT, price_open decimal(12,5) DEFAULT NULL, ticker_id int(11) NOT NULL, price_datetime datetime NOT NULL, PRIMARY KEY (price_id), UNIQUE KEY datetime (price_datetime,ticker_id) ) Expected result: +------------+---------------------+--------+---------+-----------+---------------------+------------+-----------+ | comment_id | comment_datetime | author | comment | ticker_id | price_datetime | price_open | threshold | +------------+---------------------+--------+---------+-----------+---------------------+------------+-----------+ | 1 | 2014-09-22 06:05:00 | A1 | C1 | 343 | 2014-09-22 08:00:00 | 53.25000 | C | +------------+---------------------+--------+---------+-----------+---------------------+------------+-----------+ | 2 | 2014-09-22 06:39:00 | A2 | C2 | 1 | 2014-09-22 08:00:00 | 62.00000 | Y | +------------+---------------------+--------+---------+-----------+---------------------+------------+-----------+ | 3 | 2014-09-22 08:13:00 | A3 | C3 | 178 | 2014-09-22 08:13:00 | 5.15000 | R | +------------+---------------------+--------+---------+-----------+---------------------+------------+-----------+