持續更新……html
參考:https://www.cnblogs.com/bbliutao/archive/2017/11/08/7804263.html函數
1. ADD_MONTHSspa
語法: ADD_MONTHS(date,months)code
描述:增長月份,給日期date增長months個月,months能夠是負數。htm
demo:select to_char(ADD_MONTHS(sysdate, 1-rownum),'yyyy-mm') d from dual connect by rownum<=6 blog
2019-06
2019-05
2019-04
2019-03
2019-02
2019-01get
2. DECODE
it
語法: DECODE(值,條件1,返回值1,條件2,返回值2,...條件n,返回值n,缺省值)date
描述:至關於IF ELSE,當值爲條件1返回值1,最後一個缺省值。select
demo:select decode(num,' ',0,null,0,num) from dual --若是num爲空格返回0,若是爲null返回0,其餘返回num