问题
So I'm designing a function that inserts a row into the MySQL database. The table has a Primary key with Auto-Increment enabled. So I don't insert the value of this column. But the PK is the only unique column of the entire table. How can I fetch the row I just inserted?
I don't see a problem if the function is in light traffic, but when its load is heavier and heavier, I can see a potential bug: say I inserted a row and the DB's AI value is 1, then before the fetch function starts to request the "latest inserted row", another row is inserted with the AI value 2. Now if the fetch function of Insert 1 runs, Row 2 will be fetched. I know the time gap will need to be so small to allow this bug to actually exist, but is there a better way to fetch the right row, while maintain the table only having the PK as the unique column? (I don't want to implement an additional checksum column, though I see it's a potential solution.)
回答1:
its not very logical but you could:
insert into `table1` (`column1`,`column2`,`column3`) VALUES ("value1","value2","value3");
select * from `table1` where `PK`=LAST_INSERT_ID();
instead you should only SELECT LAST_INSERT_ID(); as jurgen d suggested and reuse the other data
回答2:
Please read this php function mysqli_insert_id()
Sorry about the above, I foolishly assumed you were using php. MySQL also has a native LAST_INSERT_ID() function.
The ID that was generated is maintained in the server on a per-connection basis. This means that the value returned by the function to a given client is the first AUTO_INCREMENTvalue generated for most recent statement affecting an AUTO_INCREMENT column by that client. This value cannot be affected by other clients, even if they generate AUTO_INCREMENT values of their own. This behavior ensures that each client can retrieve its own ID without concern for the activity of other clients, and without the need for locks or transactions.
Reference; http://dev.mysql.com/doc/refman/5.5/en/information-functions.html#function_last-insert-id
来源：https://stackoverflow.com/questions/17797976/mysql-fetch-the-row-just-inserted