|| 连接运算符

||--批量修改sequence: select 'alter sequence ' || SEQUENCE_OWNER ||'.'||sequence_name|| ' cache 1000;' from dba_sequences;---批量drop 表:SQL> select 'drop table '||table_name||';' from user_tables;---计算所有表中的行数: select 'select count(*) from '||table_name||';' from user_tables;---批量kill 持有行锁进程select 'alter system kill session '||''''||SID||','||SERIAL#||''''||';' from v$session where sid in (select sid from v$lock where type in ('TM','TX') and lmode=6)