GreenPlum之按月份或季度实现行转列

1.参考GreenPlum之生成月份字典表

  GreenPlum之生成月份字典表

2.根据Case When语句及GreenPlum中string_agg聚合函数拼凑对应月份或季度周期字段，以下是核心实现sql，读者可根据需求自行修改：

  if position('yyyy-mm' in in_datecolum)>0 then 
--按照月度周期实现行转列    
  out_strsql := '
  select 

  '||case in_matrix 
  when 1 then 'string_agg('',cast(count(distinct case when 日期字段=''''''||monthid||'''''' then 表名.字段名1 end) as numeric(16,0)) as "''||monthid||''" '','''' order by monthid)' 
  when 2 then 'string_agg('',sum(case when 日期字段=''''''||monthid||'''''' then 表名.字段名2 else 0 end) as "''||monthid||''" '','''' order by monthid)' 
  when 3 then 'string_agg('',sum(case when 日期字段=''''''||monthid||'''''' then 表名.字段名3 else 0 end) as "''||monthid||''" '','''' order by monthid)' 
  when 4 then 'string_agg('',cast(count(distinct case when 日期字段=''''''||monthid||'''''' then 表名.字段名4 end) as numeric(16,0)) as "''||monthid||''" '','''' order by monthid)' 
  
  else 
  'string_agg('',sum(case when 日期字段=''''''||monthid||'''''' then 表名.字段名3 else 0 end) as "''||monthid||''" '','''' order by monthid)'
  end 
  ||'from (
  select monthid from monthmapping where onday between '''||in_startdate||''' and '''||in_overdate||''' group by monthid) tab
  ';

  execute out_strsql into aggstr;

--按照季度周期实现行转列
  else 

  out_strsql := '
  select 

  '||case in_matrix 
  when 1 then 'string_agg('',cast(count(distinct case when 日期字段=''''''||monthid||'''''' then 表名.字段名1 end) as numeric(16,0)) as "''||monthid||''" '','''' order by monthid)' 
  when 2 then 'string_agg('',sum(case when 日期字段=''''''||monthid||'''''' then 表名.字段名2 else 0 end) as "''||monthid||''" '','''' order by monthid)' 
  when 3 then 'string_agg('',sum(case when 日期字段=''''''||monthid||'''''' then 表名.字段名3 else 0 end) as "''||monthid||''" '','''' order by monthid)' 
  when 4 then 'string_agg('',cast(count(distinct case when 日期字段=''''''||monthid||'''''' then 表名.字段名4 end) as numeric(16,0)) as "''||monthid||''" '','''' order by monthid)' 
  
  else 
  'string_agg('',sum(case when 日期字段=''''''||monthid||'''''' then 表名.字段名3 else 0 end) as "''||monthid||''" '','''' order by monthid)'
  end 
  ||'from (
  select substring(onday,1,4)||''-''||EXTRACT(QUARTER from onday)||''-01'' as monthid from monthmapping where onday between '''||in_startdate||''' and '''||in_overdate||''' 
  group by substring(onday,1,4)||''-''||EXTRACT(QUARTER from onday)||''-01'') tab
  ';

  execute out_strsql into aggstr;

  end if;

  raise notice 'aggstr : %',aggstr;