The only portable way to achieve consistency between rooms and tags and making sure rooms are never returned after they had been deleted is locking them with SELECT FOR UPDATE. However in some systems locking is a side effect of concurrency control, and you achieve the same results without specifying FOR UPDATE explicitly. To solve this problem, Thread … Read more
The error message will include the name of the constraint that was violated (there may be more than one unique constraint on a table). You can use that constraint name to identify the column(s) that the unique constraint is declared on Once you know what column(s) are affected, you can compare the data you’re trying … Read more
Can someone provide a straightforward (but not simpler than possible) explanation of a transaction as applied to computing (even if copied from Wikipedia)?