下表是在Oracle文档里里面列出的操作会对表加上什么类型的lock,以及该锁和其他类型的操作的兼容性。Table 13-3 Summary of Table LocksSQL StatementMode of Table LockLock Modes Permitted?RSRXSSRXXSELECT...FROM table...noneYYYYYINSERT INTO table...RXYYNNN...【阅读全文】
oracle的系统和对象权限 alter any cluster 修改任意簇的权限 alter any index 修改任意索引的权限 alter any role 修改任意角色的权限 alter any sequence 修改任意序列的权限 alter any snapshot 修改任意快照的权限 alter any table 修改任意表的权限 alter any tr...【阅读全文】
select SAMPLE_TIME from GV_$ACTIVE_SESSION_HISTORY where rownum<2;SAMPLE_TIME---------------------------------------------------------------------------06-MAY-14 05.17.14.651 PMselect SAMPLE_TIME+0 from GV_$ACTIVE_SESSION_HISTORY where rownum<2;SAMPLE_TIME+0-------------------2014-05-06 1...【阅读全文】
1.第一种,事物级,当 commit以后数据就查不到了。关键字是commit delete rowsCREATE GLOBAL TEMPORARY TABLEt_temp2 ON COMMIT DELETE ROWSAS SELECT 1 AS ID FROM dual;2.第二种,会话级,退出会话以后,数据才查不到关键字comit preserve rowsCREATE GLOBAL TEMPORARY TABLEt_temp1 ON COMMIT PRESERVE ROWSAS S...【阅读全文】
left join加上where条件的困惑 摘自:http://hi.baidu.com/dyzhong/blog/item/b42e56a93c0bfcf71e17a2c0.html left join的困惑:一旦加上where条件,则显示的结果等于inner join 将where 换成 and 用where 是先连接然后再筛选 用and 是先筛选再连接 数据库在通...【阅读全文】