DB

ORMs And ACID

1. ORMs
2. ACID
   1. Atomicity: the “all or nothing” rule — the transaction either happens completely or doesn’t happen at all
   2. Consistency: data is consistent before and after a transaction without any missing steps
   3. Isolation: multiple transactions can happen concurrently without reading the wrong data
   4. Durability: transactional success is robust to system failure
3. Transactions
   1. rollback
   2. commit
4. N+1 查询：运行一个查询来获取类别列表，然后运行另一个查询来获取每 N 个类别