?????????

????MySQL???????????????????????
?????? Serializable (???л?)?????????????????????????????????
?????? Repeatable read (???????)????????????????????????????
?????? Read committed (??????)?????????????????
?????? Read uncommitted (??δ??)????????κ??????????????
????Mysql ?????????????? Repeatable read
????Oracle??????????????Read committed
?????????????????????????select @@tx_isolation;
????“???”???????????????“???????”??“???”??????
???????????????????????:
??????????????????????????????ζ??????????????????
???????????????????????????
?????????????????1?κ??2?ζ????????????????
??????????????????????????????????????ζ???????????.
????????????????????????????????????
???????????????????????????????
???????????????????????????????????