单个字段屏蔽重复出现的字符串

--NB的 case when
create table test0518(n1 date,n2 varchar2(50));

insert into test0518 values(sysdate,'0.11 0.12 0.11 0.14')

insert into test0518 values(sysdate,'0.11');

select n2,INSTR(n2, '0.11', 1, 1),INSTR(n2, '0.11', 1, 2) from test0518 ;

--第一次修改 屏蔽重复出现的字符串
SELECT n1,n2,CASE WHEN INSTR(n2, '0.11', 1, 2) > 0 THEN
SUBSTR(n2, 1, INSTR(n2, '0.11', 1, 2) - 1)||
REPLACE(SUBSTR(n2,INSTR(n2, '0.11', 1, 2),LENGTH(n2)),'0.11','')
else n2 end as xxxx
from test0518;

N1 N2 XXXX
------------------ ------------------------- -----------------
2017/5/19 9:36:09 0.12 ,0.13 ,0.11 ,0.11 0.12 ,0.13 ,0.11 ,
2017/5/18 9:26:06 0.11 ,0.12 ,0.11 ,0.14 0.11 ,0.12 , ,0.14
2017/5/18 9:26:09 0.11 0.11
2017/5/18 9:56:09 0.12 ,0.11 ,0.11 ,0.13 0.12 ,0.11 , ,0.13

结果有点瑕疵，0.11 去掉了 但是剩下了 多余的 逗号

--第二次修改 去除多余的逗号
SELECT n1,n2,CASE WHEN INSTR(n2, '0.11', 1, 2) > 0 THEN --如果第二次出现的位置(13)>0 ，那么重复出现了 0.11 ,0.12 ,0.11 ,0.14
SUBSTR(n2, 1, INSTR(n2, '0.11', 1, 2) - 1)|| --从左边一次性的截取到 13-1 位置 即：0.11 ,0.12 ,
REPLACE(SUBSTR(n2,INSTR(n2, '0.11', 1, 2)/*13*/,LENGTH(n2)),'0.11 ,','')
else n2 end as xxxx
from test0518;

N1 N2 XXXX
------------------ ------------------------- ------------------------
2017/5/19 9:36:09 0.12 ,0.13 ,0.11 ,0.11 0.12 ,0.13 ,0.11 ,0.11
2017/5/18 9:26:06 0.11 ,0.12 ,0.11 ,0.14 0.11 ,0.12 ,0.14
2017/5/18 9:26:09 0.11 0.11
2017/5/18 9:56:09 0.12 ,0.11 ,0.11 ,0.13 0.12 ,0.11 ,0.13

--第三次修改 改为 update case
update test0518 set n5=CASE WHEN INSTR(n2, '0.11', 1, 2) > 0 THEN --如果第二次出现的位置(13)>0 ，那么重复出现了 0.11 ,0.12 ,0.11 ,0.14
SUBSTR(n2, 1, INSTR(n2, '0.11', 1, 2) - 1)|| --从左边一次性的截取到 13-1 位置 即：0.11 ,0.12 ,
REPLACE(SUBSTR(n2,INSTR(n2, '0.11', 1, 2)/*13*/,LENGTH(n2)),'0.11 ,','')
else n2 end ;

--第四次修改
SELECT n1,n2,
CASE
WHEN INSTR(n2, '0.11', 1, 2) > 0 AND INSTR(n2, '0.11', 1, 2)< LENGTH(N2)-3 THEN --0.11 ,0.12 ,0.11 ,0.14
SUBSTR(n2, 1, INSTR(n2, '0.11', 1, 2) - 1)||
REPLACE(SUBSTR(n2,INSTR(n2, '0.11', 1, 2)+6,LENGTH(n2)),'0.11,','')
WHEN INSTR(n2, '0.11', 1, 2) > 0 AND INSTR(n2, '0.11', 1, 2)=LENGTH(N2)-3 THEN --0.12 ,0.13 ,0.11 ,0.11
SUBSTR(n2, 1, INSTR(n2, '0.11', 1, 2) -2 )
else N2 end as COL3 --0.11
from test0518;

N1 N2 XXXX
------------------ ------------------------- ------------------------
2017/5/19 9:36:09 0.12 ,0.13 ,0.11 ,0.11 0.12 ,0.13 ,0.11
2017/5/18 9:26:06 0.11 ,0.12 ,0.11 ,0.14 0.11 ,0.12 ,0.14
2017/5/18 9:26:09 0.11 0.11
2017/5/18 9:56:09 0.12 ,0.11 ,0.11 ,0.13 0.12 ,0.11 ,0.13

--第五次修改 改为 update case
update test0518 set n6=CASE
WHEN INSTR(n2, '0.11', 1, 2) > 0 AND INSTR(n2, '0.11', 1, 2)< LENGTH(N2)-3 THEN --0.11 ,0.12 ,0.11 ,0.14
SUBSTR(n2, 1, INSTR(n2, '0.11', 1, 2) - 1)||
REPLACE(SUBSTR(n2,INSTR(n2, '0.11', 1, 2)+6,LENGTH(n2)),'0.11,','')
WHEN INSTR(n2, '0.11', 1, 2) > 0 AND INSTR(n2, '0.11', 1, 2)=LENGTH(N2)-3 THEN --0.12 ,0.13 ,0.11 ,0.11
SUBSTR(n2, 1, INSTR(n2, '0.11', 1, 2) -2 )
else N2 end ;