Oracle字符串截取和拼接应用

今天有人问了个关于Oracle字符串截取和拼接的问题,让我帮他写出SQL,看了下问题描述还比较清晰就试着解决下,利用午休时间把功能实现了,问题看似不难,但思路一定要清晰,不然就乱了,关键大量应用了Oracle的substr 和instr函数。下面贴出问题和脚本:
问题:sql中一个字段值为:1788987565327、768374872394903、21437238740213483874629、23412341234252345。其中顿号间隔的每一组数字位数和尾数不定,现在要使前面这个字段值中顿号前的数字尾数即7、3、9、5都分别加1,变成8、4、0、6输出成1788987565328、768374872394904、21437238740213483874620、23412341234252346。注意其中第三个数,从9加1后,输出成0,而不是10

脚本:
declare
    targetstr varchar2(2000);
    strlength number;
    position number;
    maxposition number;
    retrunstr varchar2(2000);
    tempstr varchar2(2000);
    endstr number;
begin
    targetstr := '1788987565327、768374872394903、21437238740213483874629、23412341234252345';
    maxposition := 0;
    select LENGTH(targetstr) into strlength  from dual;
    for i in 1..strlength loop
        select instr(str,'、',1,i) into position from (select targetstr as str from dual);
        --dbms_output.PUT_LINE(position);
        if position > 0 then
            if maxposition = 0 then
                select substr(str,0,instr(str,'、',1,1)-1) into retrunstr from (select targetstr as str from dual);
                select TO_NUMBER(substr(restr,-1)) into endstr from (select retrunstr as restr from dual);
                if endstr = 3 or endstr = 5 or endstr = 7 then
                    endstr := endstr + 1;
                elsif endstr = 9 then
                    endstr := 0;
                end if;
                select substr(str,0,instr(str,'、',1,1)-2)||TO_CHAR(endstr) into retrunstr from (select targetstr as str from dual);
            elsif maxposition < position then
                select substr(str,instr(str,'、',1,i-1)+1,instr(str,'、',1,i)-instr(str,'、',1,i-1)-1) into tempstr from (select targetstr as str from dual);
                select TO_NUMBER(substr(restr,-1)) into endstr from (select tempstr as restr from dual);
                if endstr = 3 or endstr = 5 or endstr = 7 then
                    endstr := endstr + 1;
                elsif endstr = 9 then
                    endstr := 0;
                end if;
                select substr(str,1,length(str)-1) ||TO_CHAR(endstr) into tempstr from (select tempstr as str from dual);
                retrunstr := retrunstr || '、'|| tempstr;             
            end if;
            maxposition := position;
        else
            if maxposition > position then
                --特别处理最后一段
                tempstr := '';
                select substr(str,maxposition-length(str)) into tempstr from (select targetstr as str from dual);
                select TO_NUMBER(substr(restr,-1)) into endstr from (select tempstr as restr from dual);
                if endstr = 3 or endstr = 5 or endstr = 7 then
                    endstr := endstr + 1;
                elsif endstr = 9 then
                    endstr := 0;
                end if;
                select substr(str,1,length(str)-1) ||TO_CHAR(endstr) into tempstr from (select tempstr as str from dual);
                retrunstr := retrunstr || '、'|| tempstr;
            end if;
            exit;
        end if;
    end loop;
    dbms_output.PUT_LINE(retrunstr);
end;

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