Oracle中TO_DATE/TO_CHAR函数的应用

 #把时间戳转换成易读格式 

SELECT TO_CHAR(1520325660000 / (1000 * 60 * 60 * 24) + TO_DATE('1970-01-01 08:00:00', 'YYYY/MM/DD HH:MI:SS'), 'YYYY/MM/DD HH24:MI:SS') FROM DUAL

 #实时的系统时间

select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') as nowTime from dual;

#在某个创建时间段排序zymc字段，并按顺序排序

SELECT
    T .zymc,
    COUNT (*)
FROM
    LY_DGSX_BYSJ_KTBG T
WHERE
    T .czsj BETWEEN TO_DATE ('2018-10-20 00:00:00','yyyy-mm-dd hh24:mi:ss') AND TO_DATE ('2019-10-20 23:59:59','yyyy-mm-dd hh24:mi:ss')
GROUP BY
    T .zymc
ORDER BY
    COUNT (*) DESC