oracle ÖеÄminus
minusÔËËã
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exp:selectjobfromaccount
minus
selectjobfromsales;
ÓëunionÏà·´
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Ò».B-TreeË÷Òý(b-tree index)
1. Ñ¡ÏîÔñË÷Òý×ֶεÄÔÔò:
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1¡¢ÏȲéѯ¿ÕÏпռä
select tablespace_name,file_id,block_id,bytes,blocks from dba_free_space;
2¡¢Ôö¼ÓOracle±í¿Õ¼ä
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select&n ......
update t_tmprpt_firstreplycosttime t
set (t.firstreplytime,
t.dealstaff,
t.firstreplyfailcontent)
= (select a.suggesttime,
a.suggester,
substr(a.remark,instr(a.remark,'¡¿',1)+2)
from t_wf_suggesthis a
......
1. ASCII
·µ»ØÓëÖ¸¶¨µÄ×Ö·û¶ÔÓ¦µÄÊ®½øÖÆÊý;
SQL> select ascii(A) A,ascii(a) a,ascii(0) zero,ascii( ) space from dual;
A A ZERO SPACE
--------- --------- --------- ---------
65 97 48 32
2. CHR
¸ø³öÕûÊý,·µ»Ø¶ÔÓ¦µÄ×Ö·û;
SQL> select chr(54740) zhao,chr(65) chr65 from dual;
ZH ......