(1) A 表中有100条记录.
Select * FROM A Where A.COLUMN1 = A.COLUMN1
这个语句返回几条记录? (简单吧,似乎1秒钟就有答案了:)
(2) Create SEQUENCE PEAK_NO
Select PEAK_NO.NEXTVAL FROM DUAL –> 假设返回1
10秒中后,再次做
Select PEAK_NO.NEXTVAL FROM DUAL –> 返回多少?
(3) SQL> connect sys as sysdba
Connected.
SQL> insert into dual values ( ‘Y’);
1 row created.
SQL> commit;
Commit complete.
SQL> select count(*) from dual;
COUNT(*)
———-
2
SQL> delete from dual;
commit;
–>DUAL里还剩几条记录?
