10:47:39 SQL> insert into tb(colnew) values('123'||chr(38)||chr(38)||'wef');已创建 1 行。已用时间:  00: 00: 00.16
10:47:51 SQL> select * from tb where col1 is null;COL1       COL2                           COLNEW
---------- ------------------------------ --------------------
           TEMP                           123&&wef已用时间:  00: 00: 00.16