爲什麼這個簡單的連接不能工作？

Question

我試圖讓內部連接工作在那裏它從兩個表的區域代碼，並把城市名稱旁邊適當series_id

CREATE VIEW medical As 
SELECT series_id AS City, FORMAT(AVG(value),2) AS Average_CPI,  SUBSTRING(series_id,5,4) as areacode, cuArea.city_name, cuArea.area_code 
FROM CURRENT 
WHERE 
(
(
SUBSTRING(series_id,5,4) = 'A311' 
AND SUBSTRING(series_id,9,8) = 'SAM' 
AND period = 'M13' 
) 
OR 
(
SUBSTRING(series_id,5,4) = 'A316' 
AND SUBSTRING(series_id,9,8) = 'SAM' 
AND period = 'M13' 
) 
) 
GROUP BY series_id 
INNER JOIN cuArea 
ON cuArea.area_code = areacode 

Answer 1

你有錯誤的位置加入。它應該在FROM之後。

CREATE VIEW medical As 
SELECT series_id AS City, FORMAT(AVG(value),2) AS Average_CPI,  SUBSTRING(series_id,5,4) as areacode, cuArea.city_name, cuArea.area_code 
FROM CURRENT 
INNER JOIN cuArea 
ON cuArea.area_code = current.areacode 
WHERE 
(
(
SUBSTRING(series_id,5,4) = 'A311' 
AND SUBSTRING(series_id,9,8) = 'SAM' 
AND period = 'M13' 
) 
OR 
(
SUBSTRING(series_id,5,4) = 'A316' 
AND SUBSTRING(series_id,9,8) = 'SAM' 
AND period = 'M13' 
) 
) 
GROUP BY series_id