- 获取本年的第一天
trunc(current date,'YY')
- 获取去年的第一天
trunc(current date-1 year,'YY')
- 获取本年本月的第一天
trunc(current date,'MM')
- 获取去年本月的第一天
trunc(current date-1 year,'MM')
trunc(current date,'YY')
trunc(current date-1 year,'YY')
trunc(current date,'MM')
trunc(current date-1 year,'MM')