使用外键更新值和表

Question

ticketId(**)	timeExpected	timeElapsed
187	5	5
225	4	8
856	8	15
782	10	8

**primary key *foreign key

id(**)	(*)ticketId	beyondTime
1	187	0
2	225	1
3	856	1
4	782	0

I have to know which ticket his out of time and I have this in mind and in my database but I can't figure it out with SQL. I want to know when a ticket is out of time like the ticket number 225 is, I would like to update the other table with a binary 1 for "out of time" and 0 "good".

I don't know if I can update the "beyondTime" table when I do "timeExpected - timeElapsed" in the first table when a ticket exceed the time expected.

Answer 1

First, let's simplify the problem you're looking a solution for:

Comparing two data field values for the rows in a table

I believe that's basically what you're trying to do. And of course, you can make a decision based on the comparison and act accordingly like updating some values in another table if you want to.

But if all you're looking for is kind of a report, then all you need would be just a select statement equipped with the logic doing the comparison for you.

You can use SQL Case Statement for this. Here is an easy guide if you want to take a look.

The select statement you need would be like this:

select ticketId, (case when timeElapsed > timeExpected then 1 else 0 end) as beyondTime from tickets

The result would be like this:

Two things to remember:

1. Don't get disappointed by the negative points and keep asking questions:)
2. Identify the issue you need help with and be specific with your question. I'd suggest you to update this question.

Good luck!