How to use UNIQUE of PHP and MySQL to ensure that the user name is unique like JD.com registration?
I think that such a quick way to determine the user name duplication is to set the user name field UNIQUE, and then write to catch the exception.
But I tried it and found that the actual operation is not that simple. If the user name is required to be unique, just write the table to see the exception. If it is repeated, it can return false, but if it is successful, the written data will be incomplete. We What is really needed is to write the registration information submitted by the user to the table together. I thought about it and realized that this operation can only be achieved through transactions. As long as the transaction is not committed, the table will not be actually written, but we have already learned that the table Is this piece of data conflicting? I don’t know if my understanding is correct. Or it is achieved through other means. Isn’t it appropriate to judge by select query for a large amount of data?
