如何返回日期的星期值？

Question

SELECT TO_CHAR(jhrq,'YYYY/IW') FROM bdxjt_jh_xxxx

Answer 1

select decode(to_char(sysdate,'D'),
              '1','日',
              '2','一',
              '3','二',
              '4','三',
              '5','四',
              '6','五',
              '7','六') from dual;

Answer 2

select  substr(to_char(to_date('2002-08-26','yyyy-mm-dd'),'day'),3,1)  from  dual;
SUBSTR(TO_CHAR(TO_DATE('2002-0
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一