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trunc()º¯ÊýµÄѧϰ (oracle)

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A£º SELECT a.times,to_date(a.times,'yyyymmdd'),trunc(to_date(a.times,'yyyymmdd'),'month') from dmf_loan_limit a
ÏÔʾµÄ½á¹ûΪ£º
1 20080131     2008-1-31    2008-1-1
2 20080131     2008-1-31    2008-1-1
3 20080131     2008-1-31    2008-1-1
4 20080131     2008-1-31    2008-1-1
5 20080229     2008-2-29    2008-2-1
6 20080229     2008-2-29    2008-2-1
7 20080229     2008-2-29    2008-2-1
8 20080229     2008-2-29    2008-2-1
9 20080331     2008-3-31    2008-3-1
10 20080331    2008-3-31    2008-3-1
11 20080331    2008-3-31    2008-3-1
12 20080331    2008-3-31    2008-3-1
13 20080430    2008-4-30    2008-4-1
½âÊÍ£ºtrunc(to_date(a.times,'yyyymmdd'),'month')  ½«a.times ת»»³É yyyymmddµÄÈÕÆÚÐÎʽ£¬²¢ÇÒ·µ»Øa.timeËùÔÚÔµĵÚÒ»Ì졣ͨ¹ýÕâ¸ö¹«Ê½¾Í¿ÉÒÔÇó³öÕâÌìµ½ÕâÔµĵÚÒ»ÌìÏà²î¾ßÌåµÄÌìÊý¡£
B: 
SELECT a.times,to_date(a.times,'yyyymmdd'),trunc(to_date(a.times,'yyyymmdd'),'year') from dmf_loan_limit a
1 20080131      2008-1-31      2008-1-1
2 20080131      2008-1-31      2008-1-1
3 20080131      2008-1-31      2008-1-1
4 20080131      2008-1-31      2008-1-1
5 20080229     


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oracleÖбȽÏʵÓÃsqlÓï¾ä

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SELECT table_name from user_tables;
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select user,table_name from all_tables;
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select table_name,column_name from user_tab_columns;
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oracleÅúÁ¿(batch)²Ù×÷µÄʹÓÃ

    /**
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ORACLEÎﻯÊÓͼ ÀûÓÃά¶ÔÏóÀ´ÓÅ»¯Êý¾Ý²Ö¿âµÄ¸ß¼¶¼¼ÇÉ


http://www.anysql.net/oracle/oracle_olap_dimension.html
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ORACLEÆô¶¯Ô­Àí

Checkpoint
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Oracle Lock

http://download-uk.oracle.com/docs/cd/B10501_01/server.920/a96524/c21cnsis.htm#2937
Types of Locks
Oracle automatically uses different types of locks to control concurrent access to data and to prevent destructive interaction between users. Oracle automatically locks a resource on behalf of a tran ......
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