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oracle cast() º¯ÊýÎÊÌâ

¹Ø¼ü×Ö: oracle cast() º¯ÊýÎÊÌâ
SQL> create table t1(a varchar(10));
Table created.
SQL> insert into t1 values ('12.3456');
1 row created.
SQL> select round(a) from t1;
  ROUND(A)
----------
        12
SQL> select round(a,3) from t1;
ROUND(A,3)
----------
    12.346
SQL> select cast(a as int) from t1;
CAST(AASINT)
------------
          12
SQL> select cast(a as number(8,4)) from t1;
CAST(AASNUMBER(8,4))
--------------------
             12.3456
=========================================================
cast ÊǽøÐÐÀàÐÍת»»µÄ, ¿ÉÒÔÕë¶Ô¸÷ÖÖOracleÊý¾ÝÀàÐÍ. Ð޸ĵÄÊÇÓû§µÄÊý¾ÝÀàÐÍ.
roundÖ»ÊÇÐ޸ĵÄÊý¾ÝÏÔʾ¸ñʽ. ¶ÔÊý¾Ý×öËÄÉáÎåÈë. ÀàËÆµÄº¯Êý»¹ÓÐceil(È¡´ËÊý¾ÝµÄ×îСÕûÊý). trunc( È¡Õûº¯Êý.)
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SQL> select round(12.45) round,trunc(12.45) trunc,ceil(12.45) ceil
  2  from dual
  3  /
     ROUND      TRUNC       CEIL
---------- ---------- ----------
        12         12         13
SQL> select round(12.54) round,trunc(12.54) trnc,ceil(12.54) ceil
  2  from dual
  3  /
     ROUND       TRNC       CEIL
---------- ---------- ----------
        13         12         13
SQL>


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killtest ·ÖÏí×îеÄoracle 1z0 047Ìâ¿â×ÊÁÏÏÂÔØ

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1. Which statements are true? (Choose all that apply.)
A. The data dictionary is created and maintained by the database administrator.
B. The data dictionary views can consist of joins of dictiona ......

ORACLE 10 (¸¶Ê×ê¿)ѧϰ±Ê¼Ç µÚ2½Ú ÃüÁî¡£

ORACLE 10 ѧϰ±Ê¼Ç-µÚ2½Ú-ÃüÁî¡£
1. inner join / left join/ right join / full join
select a.dname, b.ename from dept a, emp b where a.deptno=b.deptno and a.deptno=10;
select a.dname, b.ename from dept a inner join emp b
on a.deptno=b.deptno and a.deptno=10;
select dname,ename from dept natural ......

oracle ֮ϵͳ±í µãµÎ »ýÀÛ

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SELECT osuser, username, sql_text from v$session a, v$sqltext b where a.sql_address =b.address order by address, piece;
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 select username,sid,opname, round(sofar*100 / totalwork,0) || '%' as progress, time_remaining,sql_text from v$session_longops , v$ ......

Oracle£º1 not in (null)¼ìË÷²»³ö½á¹û

in/not   inÔÚÅжÏNULLʱÓõÄÓë=/<>Ò»ÑùµÄ·½Ê½£¬¼´±ØÐëÓÃis   nullÀ´Åжϣ¬·ñÔòʼÖÕΪʧ°Ü¡£  
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  select   'true'   from   dual   where   (1,2)   not   in   ((2,3),(2,null));  
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oracle Set ÃüÁî½éÉÜ

oracle Set ÃüÁî½éÉÜ
http://luoke920.javaeye.com/blog/323743
1). ÉèÖõ±Ç°sessionÊÇ·ñ¶ÔÐ޸ĵÄÊý¾Ý½øÐÐ×Ô¶¯Ìá½»
SQL>SET AUTO[COMMIT] {ON|OFF|IMM[EDIATE]| n}
2)£®ÔÚÓÃstartÃüÁîÖ´ÐÐÒ»¸ösql½Å±¾Ê±£¬ÊÇ·ñÏÔʾ½Å±¾ÖÐÕýÔÚÖ´ÐеÄSQLÓï¾ä
SQL> SET ECHO {ON|OFF}
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