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How can I make a composite key where one key is an autonumber?
I want to make a table in my database where the composite key is made up of task_id and user_id. The task key i want the database to generate for each new task and then allow me to put multiple users who can use the task key. I dont want to put multiple fields like user1, user2,user3 in the same table because i want them to pay for the task separately. Is this possible?
1 Answer
- FrankLv 78 years agoFavorite Answer
I may misunderstand what you are asking, but I think you are doing this wrong.
I'll assume that user_id is a primary key in the user table.
The task_purchase table should look like:
task_purchase_id INT AUTO_INCREMENT ,
task_id INT,
purchased_by_user INT ,
when_purchased DATETIME
PRIMARY KEY (task_id),
FOREIGN KEY (purchased_by_user) REFERENCES user(user_id)
FOREIGN KEY (task_id) REFERENCES task(task_id)
If there are 10 purchases, there are 10 rows in the task table. If some of those 10 rows reference the same user_id, that's just fine. If some of those rows reference the same task_id, that's fine.
