提示:两种方法,一种是SUM(1),一种是COUNT(column_name)
SUM(1)指的是:符合要求的返回1,然后case when外部用sum进行求和,
COUNT(column_name)指的是:符合要求的记录一个唯一id,最后就相当于COUNT(id)
示例:
SELECT MIN(province_id) provinceNumber, MIN(province_name) provinceName, COUNT(project_id) a, SUM(this_issue_money) b, SUM(CASE WHEN is_not_exit = true THEN 1 END) c, SUM(this_issue_money) d, SUM(CASE WHEN is_not_exit = true AND enterprise_type_id = 1 THEN 1 END) e, SUM(CASE WHEN enterprise_type_id = 1 THEN this_issue_money END) f, SUM(CASE WHEN is_not_exit = true AND enterprise_type_id = 2 THEN 1 END) g, SUM(CASE WHEN enterprise_type_id = 2 THEN this_issue_money END) h, SUM(CASE WHEN is_not_exit = true AND enterprise_type_id = 2 THEN 1 END) j, SUM(CASE WHEN enterprise_type_id = 2 THEN this_issue_money END) k FROM l
换成COUNT,那么就是
select COUNT(CASE WHEN is_not_exit = true then id) FROM L