有人问这样的sql该怎么实现：
表数据和结构
    CODE NAME    B01    S01    B02    S02
    1          张三       数学    80  
    1          张三                            语文    75
    2          王五       数学    70  
    2          王五    
    3          李四       数学    50  
    3          李四                           语文    88

希望查询出如下结果：
    CODE SUM_STR(NAME)    B01    SUM_STR(S01)    B02    SUM_STR(S02)
    1                张三                    数学                80           语文            75
    2                王五                    数学                70  
    3                李四                    数学                50           语文             88
这个问题可以采用自定义的聚集函数来实现：

------------------------------------

-------------------

-------最后查询语句：

在项目进入性能测试阶段，终于爆发了sql运行缓慢，系统吞吐量下降，甚至一度出现oracle服务器cpu100%的情况。具体开发和测试人员报告情况，开始介入处理。

具体查找性能缓慢的过程略除。
发现一条sql运行缓慢。通过跟踪发现一下信息
select alias_p2.pendingid, alias_p2.workitemid, alias_p2.operationid, alias_p2.operationkey,

  2  alias_p2.title, alias_p2.sendercn, alias_p2.operatedes, alias_p2.pendingstate,

  3  alias_p2.parameter, alias_p2.createdate, alias_p2.deptname, alias_p2.completeddate ,

  4  alias_p2.openstate , alias_p2.name, alias_p2.processinstanceid, alias_p2.asset

  5   from ( select alias_p1.pendingid, alias_p1.workitemid, alias_p1.operationid,

  6   alias_p1.operationkey, alias_p1.title, alias_p1.sendercn, alias_p1.operatedes,

  7    alias_p1.pendingstate, alias_p1.parameter, alias_p1.createdate, alias_p1.deptname,

  8      alias_p1.completeddate , alias_p1.openstate , alias_p1.name, alias_p1.processinstanceid ,

  9        alias_p1.asset , rownum rn from(select alias_p.pendingid, alias_p.workitemid, alias_p.operationid,

 10        alias_p.operationkey, alias_p.title, alias_p.sendercn, alias_p.operatedes, alias_p.pendingstate,

 11        alias_p.parameter, alias_p.createdate, alias_p.deptname, alias_p.completeddate , alias_p.openstate ,

 12         pd.name, w.processinstanceid , eam_db.concatassetname( alias_p.operationkey, alias_p.operationid )

 13          asset from WF_Pending alias_p, WF_WorkItem w, WF_ProcessDefinition pd, WF_ProcessInstance pi

 14          where alias_p.ownerid='qinxue'   and alias_p.pendingstate in(0,3,5,7,9,10,11,12)

 15            and (alias_p.deptname=' 审控部信息处 ' or alias_p.deptname='' or alias_p.deptname is null)

 16            and w.workitemid = alias_p.workitemid   and pi.processinstanceid = w.processinstanceid

 17  and pi.completeddate is null   and pd.processdefinitionid = w.processdefinitionid  order by alias_p.createdate desc) alias_p1 where rownum <=10)

alias_p2 where rn>=1;

 

已选择 10 行。

 

 

执行计划

----------------------------------------------------------

   0      SELECT STATEMENT Optimizer=CHOOSE (Cost=10 Card=1 Bytes=2507

          )

 

   1    0   VIEW (Cost=10 Card=1 Bytes=2507)

   2    1     COUNT (STOPKEY)

   3    2       VIEW (Cost=10 Card=1 Bytes=2494)

   4    3         SORT (ORDER BY STOPKEY) (Cost=10 Card=1 Bytes=167)

   5    4           NESTED LOOPS (Cost=8 Card=1 Bytes=167)

   6    5             NESTED LOOPS (Cost=7 Card=1 Bytes=162)

   7    6               NESTED LOOPS (Cost=6 Card=1 Bytes=134)

   8    7                 TABLE ACCESS (FULL) OF 'WF_PENDING' (Cost=5

          Card=1 Bytes=111)

 

   9    7                 TABLE ACCESS (BY INDEX ROWID) OF 'WF_WORKITE

          M' (Cost=1 Card=3 Bytes=69)

 

  10    9                   INDEX (UNIQUE SCAN) OF 'SYS_C003694' (UNIQ

          UE)

 

  11    6               TABLE ACCESS (BY INDEX ROWID) OF 'WF_PROCESSDE

          FINITION' (Cost=1 Card=1 Bytes=28)

 

  12   11                 INDEX (UNIQUE SCAN) OF 'SYS_C003684' (UNIQUE

          )

 

  13    5             TABLE ACCESS (BY INDEX ROWID) OF 'WF_PROCESSINST

          ANCE' (Cost=1 Card=1 Bytes=5)

 

  14   13               INDEX (UNIQUE SCAN) OF 'SYS_C003662' (UNIQUE)

 

 

 

 

统计信息

----------------------------------------------------------

        314  recursive calls

          0  db block gets

      29433  consistent gets

          0  physical reads

          0  redo size

       2153  bytes sent via SQL*Net to client

        372  bytes received via SQL*Net from client

          2  SQL*Net roundtrips to/from client

        101  sorts (memory)

          0  sorts (disk)

         10  rows processed

其中一致读达到近3万次，关联调用出现314次。排序数值也非常多，显然第一目标是把这两个数据降下来。
通过进一步的分析。发现出现这些问题的主要原因是调用eam_db.concatassetname( alias_p.operationkey, alias_p.operationid )这个包。
开始考虑直接在sql外层做关联，不用function来实现。利用聚集函数来合并数据。
着手建立：

聚集函数： CREATE OR REPLACE FUNCTION F_ASSETLINK(P_STR VARCHAR2) RETURN VARCHAR2
AGGREGATE USING asset_link;

----------------------
创建type：CREATE OR REPLACE TYPE ASSET_LINK AS OBJECT (
STR VARCHAR2(30000),
STATIC FUNCTION ODCIAGGREGATEINITIALIZE(SCTX IN OUT ASSET_LINK) RETURN NUMBER,
MEMBER FUNCTION ODCIAGGREGATEITERATE(SELF IN OUT ASSET_LINK, VALUE IN VARCHAR2) RETURN NUMBER,
MEMBER FUNCTION ODCIAGGREGATETERMINATE(SELF IN ASSET_LINK, RETURNVALUE OUT VARCHAR2, FLAGS IN NUMBER) RETURN NUMBER,
MEMBER FUNCTION ODCIAGGREGATEMERGE(SELF IN OUT ASSET_LINK, CTX2 IN ASSET_LINK) RETURN NUMBER
)
------------------------------------------------------

创建type body：CREATE OR REPLACE TYPE BODY ASSET_LINK IS
STATIC FUNCTION ODCIAGGREGATEINITIALIZE(SCTX IN OUT ASSET_LINK) RETURN NUMBER IS
BEGIN
SCTX := ASSET_LINK(NULL);
RETURN ODCICONST.SUCCESS;
END;
MEMBER FUNCTION ODCIAGGREGATEITERATE(SELF IN OUT ASSET_LINK, VALUE IN VARCHAR2) RETURN NUMBER IS
BEGIN
SELF.STR := SELF.STR ||','|| VALUE;
RETURN ODCICONST.SUCCESS;
END;
MEMBER FUNCTION ODCIAGGREGATETERMINATE(SELF IN ASSET_LINK, RETURNVALUE OUT VARCHAR2, FLAGS IN NUMBER) RETURN NUMBER IS
BEGIN
RETURNVALUE := SELF.STR;
RETURN ODCICONST.SUCCESS;
END;
MEMBER FUNCTION ODCIAGGREGATEMERGE(SELF IN OUT ASSET_LINK, CTX2 IN ASSET_LINK) RETURN NUMBER IS
BEGIN
NULL;
RETURN ODCICONST.SUCCESS;
END;
END;
调整sql如下：
select alias_p.pendingid, alias_p.workitemid, alias_p.operationid,
   alias_p.operationkey, alias_p.title, alias_p.sendercn, alias_p.operatedes, alias_p.pendingstate,
   alias_p.parameter, alias_p.createdate, alias_p.deptname, alias_p.completeddate , alias_p.openstate ,
   pd.name, w.processinstanceid
   --,T.ASSETCLASS3  ASSET  
   ,f_assetlink(d3.typename) ASSET
   --,eam_db.concatassetname( alias_p.operationkey, alias_p.operationid )  asset
   from WF_Pending alias_p, WF_WorkItem w,
   WF_ProcessDefinition pd, WF_ProcessInstance pi
   , tb_asset_dizhiyihao T,dic_app_wfconfig wfc,dic_app_assettype3 d3
   where alias_p.ownerid='qinxue'  
   and alias_p.pendingstate in(0,3,5,7,9,10,11,12)
   and (alias_p.deptname='审控部信息处' or alias_p.deptname='' or alias_p.deptname is null)
   and w.workitemid = alias_p.workitemid  
   and pi.processinstanceid = w.processinstanceid
   and pi.completeddate is null  
   and pd.processdefinitionid = w.processdefinitionid
   AND    t.pk_businessid = alias_p.operationid
          and alias_p.operationkey = wfc.memo_1
          and wfc.wfconfig_code = t.wfconfig_code
   and t.assetclass3 = d3.assettype3_id
   group by alias_p.pendingid, alias_p.workitemid, alias_p.operationid,
   alias_p.operationkey, alias_p.title, alias_p.sendercn, alias_p.operatedes, alias_p.pendingstate,
   alias_p.parameter, alias_p.createdate, alias_p.deptname, alias_p.completeddate , alias_p.openstate ,
   pd.name, w.processinstanceid
   order by alias_p.createdate desc
得到统计数据如下：
C:\Documents and Settings\ibm>sqlplus /nolog

SQL*Plus: Release 10.2.0.1.0 - Production on 星期一 9月 10 19:27:33 2007

Copyright (c) 1982, 2005, Oracle.  All rights reserved.

SQL> conn jic/jic@name
已连接。
SQL> set autotrace traceonly
SQL> select alias_p.pendingid, alias_p.workitemid, alias_p.operationid,
  2     alias_p.operationkey, alias_p.title, alias_p.sendercn, alias_p.operatedes, alias_p.pendingstate,
  3     alias_p.parameter, alias_p.createdate, alias_p.deptname, alias_p.completeddate , alias_p.openstate ,
  4     pd.name, w.processinstanceid
  5     --,T.ASSETCLASS3  ASSET
  6     ,f_assetlink(d3.typename) ASSET
  7     --,eam_db.concatassetname( alias_p.operationkey, alias_p.operationid )  asset
  8     from WF_Pending alias_p, WF_WorkItem w,
  9     WF_ProcessDefinition pd, WF_ProcessInstance pi
 10     , tb_asset_dizhiyihao T,dic_app_wfconfig wfc,dic_app_assettype3 d3
 11     where alias_p.ownerid='qinxue'
 12     and alias_p.pendingstate in(0,3,5,7,9,10,11,12)
 13     and (alias_p.deptname='审控部信息处' or alias_p.deptname='' or alias_p.deptname is null)
 14     and w.workitemid = alias_p.workitemid
 15     and pi.processinstanceid = w.processinstanceid
 16     and pi.completeddate is null
 17     and pd.processdefinitionid = w.processdefinitionid
 18     AND    t.pk_businessid = alias_p.operationid
 19            and alias_p.operationkey = wfc.memo_1
 20            and wfc.wfconfig_code = t.wfconfig_code
 21     and t.assetclass3 = d3.assettype3_id
 22     group by alias_p.pendingid, alias_p.workitemid, alias_p.operationid,
 23     alias_p.operationkey, alias_p.title, alias_p.sendercn, alias_p.operatedes, alias_p.pendingstate,
 24     alias_p.parameter, alias_p.createdate, alias_p.deptname, alias_p.completeddate , alias_p.openstate ,
 25     pd.name, w.processinstanceid
 26     order by alias_p.createdate desc;

已选择30行。

执行计划
----------------------------------------------------------
   0      SELECT STATEMENT Optimizer=CHOOSE (Cost=19 Card=1 Bytes=205)
   1    0   SORT (GROUP BY) (Cost=19 Card=1 Bytes=205)
   2    1     NESTED LOOPS (Cost=17 Card=1 Bytes=205)
   3    2       HASH JOIN (Cost=16 Card=1 Bytes=191)
   4    3         HASH JOIN (Cost=11 Card=1 Bytes=183)
   5    4           NESTED LOOPS (Cost=8 Card=1 Bytes=167)
   6    5             NESTED LOOPS (Cost=7 Card=1 Bytes=139)
   7    6               NESTED LOOPS (Cost=6 Card=1 Bytes=134)
   8    7                 TABLE ACCESS (FULL) OF 'WF_PENDING' (Cost=5
          Card=1 Bytes=111)

   9    7                 TABLE ACCESS (BY INDEX ROWID) OF 'WF_WORKITE
          M' (Cost=1 Card=1 Bytes=23)

  10    9                   INDEX (UNIQUE SCAN) OF 'SYS_C004347' (UNIQ
          UE)

  11    6               TABLE ACCESS (BY INDEX ROWID) OF 'WF_PROCESSIN
          STANCE' (Cost=1 Card=1 Bytes=5)

  12   11                 INDEX (UNIQUE SCAN) OF 'SYS_C004334' (UNIQUE
          )

  13    5             TABLE ACCESS (BY INDEX ROWID) OF 'WF_PROCESSDEFI
          NITION' (Cost=1 Card=1 Bytes=28)

  14   13               INDEX (UNIQUE SCAN) OF 'SYS_C004329' (UNIQUE)
  15    4           TABLE ACCESS (FULL) OF 'DIC_APP_WFCONFIG' (Cost=2
          Card=24 Bytes=384)

  16    3         TABLE ACCESS (FULL) OF 'TB_ASSET_DIZHIYIHAO' (Cost=4
           Card=310 Bytes=2480)

  17    2       TABLE ACCESS (BY INDEX ROWID) OF 'DIC_APP_ASSETTYPE3'
          (Cost=1 Card=1 Bytes=14)

  18   17         INDEX (UNIQUE SCAN) OF 'PK_DIC_APP_ASSETTYPE3' (UNIQ
          UE)

 

 

统计信息
----------------------------------------------------------
          6  recursive calls
          0  db block gets
        847  consistent gets
          0  physical reads
          0  redo size
       4102  bytes sent via SQL*Net to client
        383  bytes received via SQL*Net from client
          3  SQL*Net roundtrips to/from client
          1  sorts (memory)
          0  sorts (disk)

其中排序由101变为1次
一致读降为847。下降非常客观
关联调用仅有6次。
此sql性能优化非常可观。至此优化结束：)

数据库迁移过程中需要目标数据库和原数据库结构相同和数据是最新。
为了保持最新数据和快速切换就不可以利用exp/imp的方式，利用data guard则有平台的问题。
在这种情况下，可以利用on prebuilt table选项创建mv。然后同步运行一段时间。一次切换，删除
mv，这种情况下可以保持同名的表。mv删除。达到数据同步，切换的目标。

select z.a,z.b,z.c from (select lag(t.a,2)over(order by t.a) pp_val, lag(t.a,1)over(order by t.a) p_val, t.a, lead(t.a,1)over(order by t.a) n_val, lead(t.a,2)over(order by t.a) nn_val, t.b,t.c from test2 t) z where z.a = '1' and ((z.p_val = '1' and z.pp_val = '1') or (z.p_val = '1' and z.n_val = '1') or (z.n_val = '1' and z.nn_val = '1'));

查询结果xml化： select dbms_xmlquery.getXML(' select * from test')from dual; 表的历史记录：执行：begin dbms_wm.enableversioning('tablename','VIEW_WO_OVERWRITE') 则对这个表的cud操作都会记录历史，这个在系统中做历史再好不过了。 还有终于被tom说明：分析函数原来就是矩阵运算，呵呵，终于知道这类函数的数学原理了，呵呵，真爽，总算知道怎么理解了。 还有宝贝儿遇到新项目，需要很深的会计知识了，还被老板乱说，导致不好工作，希望她不要烦恼，开心工作

配置:server.modules 
server.modules              = (
                                "mod_rewrite",
                                "mod_redirect",
                                "mod_access",
                                "mod_status",
                                "mod_scgi",
                                "mod_accesslog" )
配置
index-file.names            = ( "index.php", "index.html",
                                            "index.htm", "default.htm" )
#### accesslog module
accesslog.filename          = "c:/depot/log/access.log"
static-file.exclude-extensions = ( ".php", ".pl", ".fcgi",".scgi" )       标红的需要加上

## bind to port (default: 80)
server.port                = 8080------------------访问端口,我设置8080

## error-handler for status 404
server.error-handler-404   = "/dispatch.scgi"
-----------------------------------------------
scgi.server = ("dispatch.scgi" => ((
"host" => "127.0.0.1",
"port" => 9999,
"check-local" => "disable"
)) )

scgi.debug=3

status.status-url = "/server-status"
status.config-url = "/server-config"

-------------------------------------
## server.virtual-* options
server.document-root        = "c:/depot/public"
记得这个需要设置到public目录,不然按默认的rails生成的文档一些东西访问不来的
-----------------------------------------------------------------------------------------------------
需要注意的是你开发的程序需要放在c盘下,不然找不到config/scgi.yaml这个文件
然后lighttpd必须装在c盘下(当前版本下1.4.11)

今天给数据库执行@spcreate.sql老是出
SP2-0734:unknown command beginning "spcreate.s..." - rest of line ignored.
郁闷坏了。经过一番折腾原来是
solution Description:
 =====================
You need to enter a valid SQL*Plus command.
In this case, you cannot start svrmgrl from within SQL*Plus,
you have to start svrmgrl from the command prompt.
This error will also occur when trying to execute a
the @ symbol is mapped to the key 'Kill' from the user's keyboard.
The way to find out the current keyboard mapping in a unix environment is using the command 'stty -a'.
The way to correct problem is to map 'Kill' to some other keyboard symbol.
The command example would be 'stty kill ^U'.
Having remapped the key you would then log into SQL*Plus and execute script.
 -------------------------------纪念一下
如果出现空行报错的话 记得执行:
SET SQLBLANKLINES ON

呵呵，最近吵架比较多，我们项目和另公司合作，经常出现两家吵架的事件，小弟不信参与其中。通过具体实践，发现我现在很容易发现别人说话的漏洞。然后常常质问对方大哥无法可说，呵呵，痛快。 我想这是 我比较最近比较喜欢高手们争论话题的帖子，建议想提高吵架水平的人多学学(别用在mm身上^^)