现在有如下两张表分别为:
表A
ID Name
1 张三
2 李四
表B
ID XMMC CODE RYID
1 A项目一 XMONE 1
2 A项目二 XMTWO 1
3 A项目三 XMTHREE 1
4 B项目一 XMONE 2 要求一条SQL语句实现如下结果 表C
ID NAME XMONE XMTWO XMTHREE
1 张三 A项目一 A项目二 A项目三
2 李四 B项目一 [空] [空] 请各位大侠帮忙哈, 谢谢!
表A
ID Name
1 张三
2 李四
表B
ID XMMC CODE RYID
1 A项目一 XMONE 1
2 A项目二 XMTWO 1
3 A项目三 XMTHREE 1
4 B项目一 XMONE 2 要求一条SQL语句实现如下结果 表C
ID NAME XMONE XMTWO XMTHREE
1 张三 A项目一 A项目二 A项目三
2 李四 B项目一 [空] [空] 请各位大侠帮忙哈, 谢谢!
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参考一下
--测试数据
create table t (XH varchar2(10), DDATE date, SXF int);
insert into t
select 1,sysdate,10 from dual union all
select 1,sysdate+1,14 from dual union all
select 1,sysdate+2,23 from dual union all
select 2,sysdate,21 from dual union all
select 2,sysdate+1,24 from dual union all
select 3,sysdate,13 from dual union all
select 3,sysdate+1,22 from dual;
--
create or replace package sp_test
is
type ResultData is ref cursor;
procedure getRstData( rst out ResultData);
end sp_test;
/
create or replace package body sp_test
is
procedure getRstData( rst out ResultData)
is
begin
declare
cursor cur is select distinct (DDATE) from t;
tmp_ddate date;
str varchar2(4000);
begin
str:='select xh';
open cur;
loop
fetch cur into tmp_ddate;
exit when cur%notfound;
str:=str||',sum(decode(to_char(ddate,''yyyymmdd''),'||chr(39)||to_char(tmp_ddate,'yyyymmdd')||chr(39)||',sxf,0)) "'||to_char(tmp_ddate,'yyyymmdd')||'"';
end loop;
str:=str||' from t group by xh';
-- dbms_output.put_line(str);
close cur;
open rst for str;
end;
end;
end sp_test;
/--输出结果
1 10 14 23
2 21 24 0
3 13 22 0
1、固定列数的行列转换
如
student subject grade
--------- ---------- --------
student1 语文 80
student1 数学 70
student1 英语 60
student2 语文 90
student2 数学 80
student2 英语 100
……
转换为
语文 数学 英语
student1 80 70 60
student2 90 80 100
……
语句如下:select student,
sum(decode(subject,'语文', grade,null)) "语文",
sum(decode(subject,'数学', grade,null)) "数学",
sum(decode(subject,'英语', grade,null)) "英语"
from table
group by student;
2、不定列行列转换
如
c1 c2
--- -----------
1 我
1 是
1 谁
2 知
2 道
3 不
……
转换为
1 我是谁
2 知道
3 不这一类型的转换可以借助于PL/SQL来完成,这里给一个例子
CREATE OR REPLACE FUNCTION get_c2(tmp_c1 NUMBER)
RETURN VARCHAR2
IS
Col_c2 VARCHAR2(4000);
BEGIN
FOR cur IN (SELECT c2 FROM t WHERE c1=tmp_c1) LOOP
Col_c2 := Col_c2||cur.c2;
END LOOP;
Col_c2 := rtrim(Col_c2,1);
RETURN Col_c2;
END;select distinct c1 ,get_c2(c1) cc2 from table;
或者不用pl/sql,利用分析函数和 CONNECT_BY 实现:SELECT c1, SUBSTR (MAX (SYS_CONNECT_BY_PATH (c2, ';')), 2) NAME
FROM (SELECT c1, c2, rn, LEAD (rn) OVER (PARTITION BY c1 ORDER BY rn) rn1
FROM (SELECT c1, c2, ROW_NUMBER () OVER (ORDER BY c2) rn
FROM t))
START WITH rn1 IS NULL
CONNECT BY rn1 = PRIOR rn
GROUP BY c1;
3、列数不固定(交叉表行列转置)
这种是比较麻烦的一种,需要借助pl/sql:原始数据:
CLASS1 CALLDATE CALLCOUNT
1 2005-08-08 40
1 2005-08-07 6
2 2005-08-08 77
3 2005-08-09 33
3 2005-08-08 9
3 2005-08-07 21转置后:
CALLDATE CallCount1 CallCount2 CallCount3
------------ ---------- ---------- ----------
2005-08-09 0 0 33
2005-08-08 40 77 9
2005-08-07 6 0 21试验如下:
1). 建立测试表和数据
CREATE TABLE t(
class1 VARCHAR2(2 BYTE),
calldate DATE,
callcount INTEGER
);INSERT INTO t(class1, calldate, callcount)
VALUES ('1', TO_DATE ('08/08/2005', 'MM/DD/YYYY'), 40);INSERT INTO t(class1, calldate, callcount)
VALUES ('1', TO_DATE ('08/07/2005', 'MM/DD/YYYY'), 6);INSERT INTO t(class1, calldate, callcount)
VALUES ('2', TO_DATE ('08/08/2005', 'MM/DD/YYYY'), 77);INSERT INTO t(class1, calldate, callcount)
VALUES ('3', TO_DATE ('08/09/2005', 'MM/DD/YYYY'), 33);INSERT INTO t(class1, calldate, callcount)
VALUES ('3', TO_DATE ('08/08/2005', 'MM/DD/YYYY'), 9);INSERT INTO t(class1, calldate, callcount)
VALUES ('3', TO_DATE ('08/07/2005', 'MM/DD/YYYY'), 21); COMMIT ; 2). 建立ref cursor准备输出结果集
CREATE OR REPLACE PACKAGE pkg_getrecord
IS
TYPE myrctype IS REF CURSOR;
END pkg_getrecord;
/3). 建立动态sql交叉表函数,输出结果集
CREATE OR REPLACE FUNCTION fn_rs
RETURN pkg_getrecord.myrctype
IS
s VARCHAR2 (4000);
CURSOR c1 IS
SELECT ',sum(case when Class1='
|| class1
|| ' then CallCount else 0 end)'
|| ' "CallCount'
|| class1
|| '"' c2
FROM t
GROUP BY class1;
r1 c1%ROWTYPE;
list_cursor pkg_getrecord.myrctype;
BEGIN
s := 'select CallDate ';
OPEN c1;
LOOP
FETCH c1 INTO r1;
EXIT WHEN c1%NOTFOUND;
s := s || r1.c2;
END LOOP;
CLOSE c1;
s := s || ' from T group by CallDate order by CallDate desc ';
OPEN list_cursor FOR s;
RETURN list_cursor;
END fn_rs;
/ 4). 测试在sql plus下执行:
var results refcursor;
exec :results := fn_rs;
print results;
CALLDATE CallCount1 CallCount2 CallCount3
--------------- ---------- ---------- ----------
2005-08-09 0 0 33
2005-08-08 40 77 9
2005-08-07 6 0 21
UNION
select 2 id ,'項目二' XMMC,'XMTWO' CODE,1 RYID FROM DUAL
UNION
select 3 id ,'項目三' XMMC,'XMTHREE' CODE,1 RYID FROM DUAL
UNION
select 4 id ,'項目一' XMMC,'XMONE' CODE,2 RYID FROM DUAL
)
WITH B AS (SELECT 1 ID,'張三' NAME FROM DUAL
UNION
SELECT 2 ID,'李四' NAME FROM DUAL
)
SELECT C.RYID,B.NAME,MAX(DECODE(RN,1,XMMC,NULL)) XMONE,
MAX(DECODE(RN,2,XMMC,NULL)) XMTWO,
MAX(DECODE(RN,3,XMMC,NULL)) XMTHREE
FROM (SELECT RYID,XMMC,CODE,ROW_NUMBER()OVER(PARTITION BY RYID ORDER BY RYID) RN FROM A) C,B
WHERE C.RYID=B.ID
GROUP BY C.RYID,B.NAME
ORDER BY C.RYID RYID NAME XMONE XMTWO XMTHREE
---------- ---- ------ ------ -------
1 張三 項目一 項目二 項目三
2 李四 項目一
case when B.Code=XMONE then B.XMMC else '' end XMONE,
case when B.Code=XMTWO then B.XMMC else ''end XMTWO,
case when B.Code=XMTHREE then B.XMMC else ''end XMTHREE
from A
left join B on A.ID=B.XMTHREEE
关键在于动态生成decode语句,拼接查询列!
--建表
create table testa
(
id int,
name varchar2(20)
);
create table testb
(
id int ,
xmmc varchar2(20),
code varchar2(20),
ryid int
);
--原始数据
insert into testa values( 1,'张三' );
insert into testa values( 2,'李四 ' );
insert into testb values( 1,'A项目一','XMONE',1 );
insert into testb values( 2,'A项目二','XMTWO', 1 );
insert into testb values( 3,'A项目三','XMTHREE',1 );
insert into testb values( 4,'B项目一','XMONE',2 );
--创建视图
create or replace view v_one
as
select a.id,a.name,b.xmmc as xmone
from testa a,testb b
where a.id= b.ryid and code='XMONE'create or replace view v_two
as
select a.id,a.name,b.xmmc as xmtwo
from testa a,testb b
where a.id= b.ryid and code='XMTWO'create or replace view v_three
as
select a.id,a.name,b.xmmc as xmthree
from testa a,testb b
where a.id= b.ryid and code='XMTHREE'
--生成报表
select a.*,b.xmtwo ,c.xmthree from v_one a,v_two b ,v_three c where a.id=b.id(+) and a.id=c.id(+)