sql 获取上个月第一天和最后一天

 

当期日期减去上个月相同当天的天数

select   dateadd(dd,-day(dateadd(month,-1,getdate()))+1,dateadd(month,-1,getdate()))     /*上个月一号*/

select   dateadd(dd,-day(getdate()),getdate())                                                                      /* 上月月底 */

select   dateadd(dd,-day(getdate())+1,getdate())                                                                  /* 本月一号 */

select   dateadd(dd,-day(dateadd(month,1,getdate())),dateadd(month,1,getdate()))            /* 本月底 */

select   dateadd(dd,-day(dateadd(month,1,getdate()))+1,dateadd(month,1,getdate()))        /* 下月一号 */

select   dateadd(dd,-day(dateadd(month,2,getdate())),dateadd(month,2,getdate()))            /* 下月月底 */

如果想把时间格式转换成“yyyy/mm/dd hh:mi:ss”这种格式，可以：

select rtrim(convert(char,getdate(),111))+''+(convert(char,getdate(),108))  -- yyyy/mm/dd hh:mi:ss

测试：(列出上月开始和结束时间，然后转换时间格式)

 declare @time1 datetime,

              @time2 datetime,

              @time3  datetime,

              @time4 datetime

 

         set @time1 = dateadd(dd,-day(dateadd(month,-1,getdate()))+1,dateadd(month,-1,getdate())),    --上个月一号

               @time2 = dateadd(dd,-day(getdate())+1,getdate())               --本月一号

         set @time3 = rtrim(convert(char,@time1,111))+''+(convert(char,@time1,108)),

               @time4 = rtrim(convert(char,@time2,111))+''+(convert(char,@time2,108))

 

        select dateadd(dd,-day(dateadd(month,-1,getdate()))+1,dateadd(month,-1,getdate()))  

        select dateadd(dd,-day(getdate())+1,getdate())

        select rtrim(convert(char,@time1,111))+''+(convert(char,@time1,108))  -- yyyy/mm/dd hh:mi:ss

        select rtrim(convert(char,@time2,111))+''+(convert(char,@time2,108))  -- yyyy/mm/dd hh:mi:ss

输出结果：(sybase下)

Jan  1 2011  5:30PM                             

-                             

Feb  1 2011  5:30PM                                                                     

-                                                            

2011/01/01 17:30:58                                                                                                   

-                                                            

2011/02/01 17:30:58