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 ;