Oracle 日期时间的转换获取

二、最近3个月的“门诊人次”和前一年的相同月份的“门诊人次” 

select  extract(year from sysdate) as 年份,(to_char(sysdate,"MM")-1) as 月份,"门诊人次" as 统计项目,count(门诊人次) from v_pt_门诊人次 where  to_char(日期,"YYYY/MM") = to_char(sysdate-30,"YYYY/MM") 
uNIOn all
select  extract(year from sysdate) as 年份,(to_char(sysdate,"MM")-2) as 月份,"门诊人次" as 统计项目,count(门诊人次) from v_pt_门诊人次 where  to_char(日期,"YYYY/MM") = to_char(sysdate-60,"YYYY/MM") 
union all
select  extract(year from sysdate) as 年份,(to_char(sysdate,"MM")-3) as 月份,"门诊人次" as 统计项目,count(门诊人次) from v_pt_门诊人次 where  to_char(日期,"YYYY/MM") = to_char(sysdate-90,"YYYY/MM") 
union all 
select  extract(year from sysdate)-1as 年份,(to_char(ADD_MONTHS(sysdate, -12),"MM")-1) as 月份,"门诊人次" as 统计项目,count(门诊人次) from v_pt_门诊人次 where  to_char(日期,"YYYY/MM") = to_char(ADD_MONTHS(sysdate, -12),"YYYY/MM") 
union all
select  extract(year from sysdate)-1 as 年份,(to_char(ADD_MONTHS(sysdate, -12),"MM")-2) as 月份,"门诊人次" as 统计项目,count(门诊人次) from v_pt_门诊人次 where  to_char(日期,"YYYY/MM") = to_char(ADD_MONTHS(sysdate, -13),"YYYY/MM") 
union all
select  extract(year from sysdate)-1 as 年份,(to_char(ADD_MONTHS(sysdate, -12),"MM")-3) as 月份,"门诊人次" as 统计项目,count(门诊人次) from v_pt_门诊人次 where  to_char(日期,"YYYY/MM") = to_char(ADD_MONTHS(sysdate, -14),"YYYY/MM") 

三、最近一个月的“门诊收入”
select  sysdate-30 as 起始日期,sysdate as 截止日期,收入分类 as 统计项目,count(金额) from v_pt_收入分析 where  类别="门诊" and 日期 between  sysdate-30 and sysdate group by 收入分类

五、最近一个月的“住院收入”
select  sysdate-30 as 起始日期,sysdate as 截止日期,收入分类 as 统计项目,count(金额) from v_pt_收入分析 where 类别="住院" and 日期 between  sysdate-30 and sysdate  group by 收入分类

四、最近3个月的“出院人数”和前一年的相同月份的“出院人数”
select  extract(year from sysdate) as 年份,(to_char(sysdate,"MM")-1) as 月份,"出院人数" as 统计项目,count(出院人数) from v_pt_住院人次 where  to_char(日期,"YYYY/MM") = to_char(sysdate-30,"YYYY/MM") 
union all
select  extract(year from sysdate) as 年份,(to_char(sysdate,"MM")-2) as 月份,"出院人数" as 统计项目,count(出院人数) from v_pt_住院人次 where  to_char(日期,"YYYY/MM") = to_char(sysdate-60,"YYYY/MM") 
union all
select  extract(year from sysdate) as 年份,(to_char(sysdate,"MM")-3) as 月份,"出院人数" as 统计项目,count(出院人数) from v_pt_住院人次 where  to_char(日期,"YYYY/MM") = to_char(sysdate-90,"YYYY/MM") 
union all 
select  extract(year from sysdate)-1as 年份,(to_char(ADD_MONTHS(sysdate, -12),"MM")-1) as 月份,"出院人数" as 统计项目,count(出院人数) from v_pt_住院人次 where  to_char(日期,"YYYY/MM") = to_char(ADD_MONTHS(sysdate, -12),"YYYY/MM") 
union all
select  extract(year from sysdate)-1 as 年份,(to_char(ADD_MONTHS(sysdate, -12),"MM")-2) as 月份,"出院人数" as 统计项目,count(出院人数) from v_pt_住院人次 where  to_char(日期,"YYYY/MM") = to_char(ADD_MONTHS(sysdate, -13),"YYYY/MM") 
union all
select  extract(year from sysdate)-1 as 年份,(to_char(ADD_MONTHS(sysdate, -12),"MM")-3) as 月份,"出院人数" as 统计项目,count(出院人数) from v_pt_住院人次 where  to_char(日期,"YYYY/MM") = to_char(ADD_MONTHS(sysdate, -14),"YYYY/MM")