How can I calculated dates from another column and another table? - mysql

Question

I have 2 tables:
table 1:
|| *handtool_id* || *maintenance_interval_value* || *unit_unit_id* || *handtool_last_date_of_maintenance* || *handtool_next_date_of_maintenance* ||
|| 1 || 1 || 5 || 2014-11-07 || ||
|| 2 || 1 || 6 || 2014-11-07 || ||
|| 3 || 4 || 4 || 2014-11-07 || ||
table 2:
|| *unit_id* || *unit_name* || *unit_value* || *unit_parent_id* ||
|| 1 || Minute || 1 || 1 ||
|| 2 || Hour || 60 || 1 ||
|| 3 || Day || 1440 || 1 ||
|| 4 || Week || 10080 || 1 ||
|| 5 || Month || 32767 || 1 ||
|| 6 || Year || 525949 || 1 ||
What is the right syntax for calculating the handtool_next_date_of_maintenance from maintenance_interval_value and from unit_unit_id? Thank you

Answer 1

I have to say, it's wrong, and very confusing to change your question like this. You should rollback this question to the one Andrew Jones answered Nov 3, accept and upvote his answer, and then ask a new question.
That said, this would appear to get you something like what you're after (although how you arrived at figures of 32767 and 525949 is beyond me !?!)
SELECT *
, h.handtool_last_date_of_maintenance
+ INTERVAL h.maintenance_interval_value
* u.unit_value MINUTE x
FROM handtools h
JOIN units u
ON u.unit_id = h.unit_unit_id;

Answer 2

Whenever you insert to B, you want to insert into A. This is a good use of a MySQL trigger. I'm assuming an auto increment for web_content_id.
DELIMITER //
CREATE TRIGGER new_language_id
AFTER INSERT ON B
FOR EACH ROW
BEGIN
INSERT INTO A (web_content_const, i18n_language_codes_i18n_language_codes_id)
VALUES ('SERVICES_HEADING', #i18n_language_codes_id),
('SERVICES_MAIN_TEXT', #i18n_language_codes_id),
('SERVICES_1_HEADING', #i18n_language_codes_id),
('SERVICES_1_TEXT', #i18n_language_codes_id);
END;//
DELIMITER ;