????????????????????????
???????????? ???????[ 2014/2/17 9:31:30 ] ????????????? ??? ?洢
???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
??????????????????????????
????1.?????е??????????8020????????????????????????????????????????????д?????洢???????????Ч???
????2.????????????????ξ???????????????????????????????綽?????????????????????????????????洢?????????????????????????????????????????????????????????????????????????????ι????
????3.???????????????char???????????varchar ????8000????char??????????洢???varchar?????????Щ???????洢??????????ε????????????????????????????????仯???????ο??????CHAR??????????????仯?????ο??????VARCHAR??
????4.??ε????????????????????????????£???t???????????Щ?????????????????Ч???????????????????????????????????????
????????????????:
????1.?????????????
????2.????????????????????????????????????????
????3.??????????? where ???????? or ?????????????????????????????????????????????裬?磺
????select id from t where num=10 or num=20
?????????????????
select id from t where num=10
union all
select id from t where num=20
????4.???????where???????????????????????????????????
??????
???·???
??????????????????
2023/3/23 14:23:39???д?ò??????????
2023/3/22 16:17:39????????????????????Щ??
2022/6/14 16:14:27??????????????????????????
2021/10/18 15:37:44???????????????
2021/9/17 15:19:29???·???????·
2021/9/14 15:42:25?????????????
2021/5/28 17:25:47??????APP??????????
2021/5/8 17:01:11