Question

我有以下问题：

我有mysql表：

continent,  
country,  
city,  
zip,  
street,  
status (int),  
reason (varchar, can be empty or some text),  
... (some other columns, not required for query)

我希望通过 country，city，zip，street 计算每个状态的出现次数，但是将状态int映射到文本：

SELECT country,city,zip,street, 
   CASE WHEN (status = '2' AND reason <> '') THEN "BLOCKED" 
        WHEN (status = '2' AND reason='') THEN "DISPUTED"  
        WHEN status = '3' THEN 'EXPIRED' 
        WHEN status = '1' THEN 'ACTIVE' ELSE 'UNKNOWN' 
        END as status, 
    count(*) AS count
FROM people
where continent='Europe'
GROUP BY country,city,zip,street,status

我认为问题出现在GROUP BY中但不确定 - 它不会返回正确的数据。

SQLFiddle （检查Paris / Street2 - 它显示3 DISPUTED，应该显示1 BLOCKED和2 DISPUTED）

感谢您的意见。

Answer 1

我认为EngineerCoder 打算写：

select country,city,zip,street, status, count(*) 
from
(
SELECT country,city,zip,street, 
   CASE WHEN (status = '2' AND reason <> '') THEN "BLOCKED" 
        WHEN (status = '2' AND reason='') THEN "DISPUTED"  
        WHEN status = '3' THEN 'EXPIRED' 
        WHEN status = '1' THEN 'ACTIVE' ELSE 'UNKNOWN' 
   END as status, 
FROM people
where continent='Europe'
) AS ilv
GROUP BY country,city,zip,street,status

MySQL计数与案例返回错误计数

1 个答案: