创建 A 列的计数以按 B 列分配

Question

我想按州统计在美国进行的审判次数。我需要的信息来自 nct_id、state 和 country 列。我在 Macbook Pro 上的 pgAdmin 中。下面是一个小样本：

nct_id        state       country
NCT04832854   Illinois    United States
NCT04832851   Michigan    United States
NCT04832802   California  United States
NCT04832813   Naples      Italy
NCT04832813   Illinois    United States

我想按州对 nct_id 进行分组，但前提是该国家/地区是“美国”。到目前为止我有这个。我收到一条错误消息：ERROR: syntax error at or near "AS" LINE 3: COUNT(nct_id) AS Count_Trials。我不确定这里的语法错误是什么。

SELECT nct_id, state
FROM facilities
COUNT(nct_id) AS Count_Trials
GROUP BY state
HAVING Country = 'United States'

我希望输出如下所示：

state      Count_Trials
Illinois   2
Michigan   1
California 1

Answer 1

你的答案如下

SELECT  state, count(nct_id) count_trials
FROM facilities
where country  = 'United States'  group by state, country order by count(nct_id) desc

测试

select   state , count(nct_id) count_trials from (            
select 'NCT04832854' nct_id  ,  'Illinois' state,    'United States'country union all
select 'NCT04832851' ,  'Michigan',    'United States' union all
select 'NCT04832802' ,  'California',  'United States' union all
select 'NCT04832813' ,  'Naples',      'Italy' union all
select 'NCT04832813' ,  'Illinois',    'United States'
) a where country  = 'United States'  group by state, country order by count(nct_id) desc