oracle日期类型的处理

1.日期和字符转换函数用法（to_date,to_char）selectto_char(sysdate,'yyyy-mm-ddhh24:mi:ss')asnowTimefromdual;//日期转化为字符串selectto_char(sysdate,'yyyy')asnowYearfromdual;//获取时间的年selectto_char(sysdate,'mm')asnowMonthfromdual;//获取时间的月selectto_char(sysdate,'dd')