Trigger To Update A Field When Field In Another Table Is Changed

I have a mysql database and I want a Trigger To Update A Field When Field In Another Table Is Changed.

Table 1 = cases_cstm and Table 2 = Contracts
I have an End date field in both tables.
The Field name under cases_cstm is enddate_c
The field name under Contracts is end_date

I would like when a Case is created to copy the End date from Contracts to Cases
Pat ShorttManagerAsked:
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ste5anSenior DeveloperCommented:
Review your model. This is redundancy at its best.
Pat ShorttManagerAuthor Commented:
I don't understand your comment?
ste5anSenior DeveloperCommented:
Normalization. Why copying a value at all? This value should be stored only once.
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Pat ShorttManagerAuthor Commented:
Cause I need to display the same date in 2 different views. one in Cases and one in Contracts.
If the date has equal value in all tables involved then it really IS redundancy... If you allow different values for whatever reason then we cannot talk about redundancy.

I just don't understand what is the problem in trigger creation.
Simply create a trigger on "Another table" where the date is updated and update the date field in all your other tables in this trigger.

BUT when you are creating the case then you don't need any trigger to set its initial date value. It has nothing to do with triggers.
NerdsOfTechTechnology ScientistCommented:
On inserting a new case, you can SELECT query contracts' end date and insert it into the case record (assuming that it has and ID) via SUBQUERY.

What is confusing is if you are recording the end date of the case separately from the contracts table for whatever reason AND why.

Maybe a question to ask is: if the contracts end date ever changes, are you expecting the cases record(s) to change also? If the contract end date is the accurate value (and a redundancy is present), the solution is simply a LEFT JOIN to contracts to output the correct end date in view(s); thus, in this scenario, make the end_date in cases obsolete/irrelevant/redundant/to-be-deleted. If the end dates are separate, in your current design, the cases' end dates will end up disjointed/non-matching from contracts (where case end dates would become outdated eventually) once contracts' end date is changed... is this expected?

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MySQL Server

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