1.參考GreenPlum之生成月份字典表
2.根據Case When語句及GreenPlum中string_agg聚合函數拼湊對應月份或季度週期字段，以下是核心實現sql，讀者可根據需求自行修改：
--字段按照月份行轉列if position('yyyy-mm' in in_datecolum)>0 then
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;
--字段按照季度實現行轉列
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;