Oracle的函数：截取和合并

select to_char(t.create_time,'yyyy-mm-dd')as date_,remark,       substr(t.remark, 1, 4) as yyyy,       substr(t.remark, 5, 2) as dd,       (case         when substr(t.remark, 7, 2) = '00' then          '01'         else          substr(t.remark, 7, 2)       end) as dd              ,       (substr(t.remark, 1, 4)||'-'||substr(t.remark, 5, 2)||'-'||       (case         when substr(t.remark, 7, 2) = '00' then          '01'         else          substr(t.remark, 7, 2)       end))as cjd  from temp_xxx t;

update temp_xxx t1 set t1.create_time=to_date(substr(t1.remark, 1, 4)||substr(t1.remark, 5, 2)||       (case         when substr(t1.remark, 7, 2) = '00' then          '01'         else          substr(t1.remark, 7, 2)       end),'yyyymmdd');