为什么这个简单的加入不起作用？

Question

我正在尝试让内部联接工作，它从两个表中获取区号并将城市名称放在适当的旁边 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

您在错误的位置加入了 JOIN。它应该在 FROM 之后。

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

为什么这个简单的加入不起作用？

Why won't this simple join work?

mysql

join

inner-join