group_concat-自动拼接case-when语句

• 导出模板
• 导出拼接语句

导出模板

select group_concat(
	'\n sum(case when col_flag = ', 
	col_flag,
    ' then 1 else 0 end) as ', 
    '"', col_flag, '"'
    )
from
     (select distinct col_flag from `table_name` group by col_flag)
as A;

导出拼接语句

 sum(case when col_flag = key1 then 1 else 0 end) as "key1",
 sum(case when col_flag = key2 then 1 else 0 end) as "key2",
 ...
 sum(case when col_flag = keyn then 1 else 0 end) as "keyn",