Advantage of analytic Function

This example shows you that  Usage of  Analytic function will make query good in performance
 
select mxid,obj#,dataobj#,owner#,name,j.namespace,type#,ctime,mtime,stime,status,flags,spare1,spare2 from sys.obj$ j,(select max(dataobj#) mxid,namespace from sys.obj$ where owner#=61 group by namespace)w where owner#=61 and j.dataobj#=w.mxid and obj# in (51606,52492,52602) ;
 
explain plan set statement_id ='r' into plan_table for select mxid,obj#,dataobj#,owner#,name,j.namespace,type#,ctime,mtime,stime,status,flags,spare1,spare2 from sys.obj$ j,(select max(dataobj#) mxid,namespace from sys.obj$ where owner#=61 group by namespace)w where owner#=61 and j.dataobj#=w.mxid  and obj# in (51606,52492,52602) ;
 
SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY('PLAN_TABLE',NULL));
 

 
Total Cost=718
 
select max(dataobj#) over(partition by owner#,namespace order by owner#,namespace) mx,obj#,dataobj#,owner#,name,namespace,type#,ctime,mtime,stime,status,flags,spare1,spare2 from sys.obj$ where owner#=61 and obj# in (51606,52492,52602);
 

 

 
explain plan set statement_id ='r' into plan_table for select max(dataobj#) over(partition by owner#,namespace order by owner#,namespace) mx, obj#,dataobj#,owner#,name,namespace,type#,ctime,mtime,stime,status,flags,spare1,spare2 from sys.obj$ where owner#=61 and obj# in (51606,52492,52602);
 
SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY('PLAN_TABLE',NULL));
 

 
Total Cost is 29
 
.`. Usage of second sql script is advisable ; where oracle optimizer works default on cost based (ie:CBO)
-----------------------------

Instead of Stragg /// Allow Duplicate

SELECT
deptno,
LTRIM(SYS_CONNECT_BY_PATH(ename, ','), ',') employees
FROM (
SELECT deptno,
ename,
row_number() over(PARTITION BY deptno ORDER BY deptno) rnum,
count(*) over(PARTITION BY deptno) tot
FROM scott.emp
)
WHERE rnum=tot
START WITH rnum = 1
CONNECT BY PRIOR rnum = rnum -1 AND PRIOR deptno = deptno;


select tb.deptno , substr ( sys_connect_by_path( tb.EMPNO, ',' ) , 2) as string
from ( select deptno ,EMPNO ,row_number() over ( partition by deptno
order by EMPNO ) as val_index from
scott.emp WHERE EMPNO IS NOT NULL ) tb where
connect_by_isleaf = 1 connect by val_index = prior val_index + 1 and
deptno = prior deptno start with val_index = 1 ;


WITH tab AS
(
SELECT &strg str
FROM DUAL)
SELECT REGEXP_SUBSTR (str, '[^,]+', 1, LEVEL) RESULT
FROM tab
CONNECT BY LEVEL <=
((SELECT SUM (CASE
WHEN SUBSTR (str, LEVEL, 1) = ','
THEN 1
WHEN LENGTH (str) = LEVEL
THEN 1
ELSE 0
END
)
FROM tab
CONNECT BY LEVEL <= LENGTH (str)));


SELECT REPLACE(&strg ,',',CHR(13)) FROM DUAL;


FROM 10G ONWARDS

SELECT deptno,wmsys.wm_concat(ename) d
FROM scott.emp group BY deptno

------------------------------------------
To remove duplicate  from a SQL

SELECT JOB, ENAME FROM
(SELECT DISTINCT ENAME,JOB, row_number () OVER (PARTITION BY ENAME ORDER BY ENAME) rn
FROM scott.emp )
WHERE rn = 1

Alphabets,Level, Analytic Query

Alphabets

WITH AlphaBet AS
( SELECT CHR((ROWNUM + 64)) AS Character
FROM DUAL CONNECT BY level <= 157)
SELECT * FROM AlphaBet;

------------------------------------------------------------------------
Some Analytic Functions

SELECT G.*,ROW_NUMBER() OVER(PARTITION BY G.DEPTNO ORDER BY G.EMPNO)
FROM EMP G;

SELECT G.DEPTNO,G.ENAME,SUM(G.SAL) OVER (PARTITION BY G.DEPTNO ORDER BY G.DEPTNO) FROM EMP G ;

SELECT FIRST_VALUE(G.EMPNO) OVER() FROM EMP G;

---------------------------------------------------------------------------
Level Query


select level,lpad(' ',3*(level)) || VC_designation s,nn_desgcode dsg,nn_repdesgcode rcd,
SYS_CONNECT_BY_path (nn_repdesgcode,'/') op,
substr(SYS_CONNECT_BY_path (nn_repdesgcode,'/'),3,
length((SYS_CONNECT_BY_path (nn_repdesgcode,'/')))) hjdd
from hr_designation_mast where nn_repdesgcode is not null
start with nn_repdesgcode is not null
connect by prior nn_desgcode=nn_repdesgcode