oracle sys_connect_by_root,CONNECT_BY_ROOT实现行列转换
10g以下版本的ORACLE可以通過DECODE等實現(xiàn)行列轉(zhuǎn)換，[@more@]ORACLE 10g開始新增的CONNECT_BY_ROOT能比較方便地實現(xiàn)行列轉(zhuǎn)換。
例：
有一表ABC,字段信息包括region(地區(qū))，name(國家)，population(人口)。
表中記錄信息如下：
region name population
A A1 1000
A A2 5000
B B1 2000
B B2 3000
......
要求用sql查詢語句實現(xiàn)以下結(jié)果：
A_num B_num ......
6000 5000 ......
實現(xiàn)：
SQL>Create Table ABC (
region Char(10),
Name Char(20),
population Number
);
/
SQL>Insert Into ABC Values('A','A1',1000);
/
SQL>Insert Into ABC Values('A','A2',5000);
/
SQL>Insert Into ABC Values('B','B1',2000);
/
SQL>Insert Into ABC Values('B','B2',3000);
/
SQL>Insert Into ABC Values('C','C1',4000);
/
SQL>Select * From ABC;
/
region name population
A A1 1000
A A2 5000
B B1 2000
B B2 3000
C C1 4000
......
SQL>
SELECT
odr,
replace(path,'_','') path
FROM
(SELECT
1 odr,
Count(*) over()-Rownum idx,
path
FROM
(SELECT
SYS_CONNECT_BY_PATH(content, '_') Path
FROM
(SELECT
num,
num1,
content
FROM
( With t As (Select no,nsum,Rownum num From ( Select Distinct REGION no,Sum(POPULATION) over(Partition By REGION ) nsum From ABC ) ) Select num,num+1 num1,no content From t )
) Start With num=1 Connect By NOCYCLE num = Prior num1
)
)
WHERE idx=0
UNION
SELECT
odr,
replace(path,'_','') path
FROM
(SELECT
2 odr,
Count(*) over()-Rownum idx,
path
FROM
(SELECT
SYS_CONNECT_BY_PATH(content, '_') Path
FROM
(SELECT
num,
num1,
content
FROM
( With t As (Select no,nsum,Rownum num From ( Select Distinct REGION no,Sum(POPULATION) over(Partition By REGION ) nsum From ABC ) ) Select num,num+1 num1,to_char(nsum)||' ' content From t )
) Start With num=1 Connect By NOCYCLE num = Prior num1
)
)
WHERE idx=0;
/
odr path
1 A B C
2 6000 5000 4000
來自 “ ITPUB博客 ” ，鏈接：http://blog.itpub.net/174388/viewspace-914475/，如需轉(zhuǎn)載，請注明出處，否則將追究法律責任。
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