sql - 如何将此 SQL 查询转换为 MS Access 查询？

Question

我在 SQL 中有查询

SELECT        COUNT(DISTINCT dbo.Polling_Stations.P_ID) AS [Male Stations]
FROM            dbo.Agent INNER JOIN
                     dbo.Polling_Stations ON dbo.Agent.P_ID = dbo.Polling_Stations.P_ID
GROUP BY dbo.Polling_Stations.Gender
HAVING        (dbo.Polling_Stations.Gender = N'Male')

我已将其转换为 Access：

SELECT        COUNT(DISTINCT Polling_Stations.P_ID) AS [Male Stations]
FROM            Agent INNER JOIN
                     Polling_Stations ON Agent.P_ID = Polling_Stations.P_ID
GROUP BY Polling_Stations.Gender
HAVING        (Polling_Stations.Gender = 'Male') 

但它给了我一个错误：查询表达式'Count（DISTINCT Polling_Stations.P_ID）'中的语法错误（缺少运算符）。

Answer 1

Access SQL 不支持COUNT(DISTINCT ...)，因此您需要这样做

SELECT COUNT(*) AS [Male Stations]
FROM
(
    SELECT DISTINCT Polling_Stations.P_ID
    FROM Agent INNER JOIN Polling_Stations 
        ON Agent.P_ID = Polling_Stations.P_ID
    WHERE Polling_Stations.Gender = "Male"
)

Answer 2

访问不支持Count(DISTINCT ...)。 SELECT DISTINCT在子查询中，并从父查询中进行计数。

SELECT COUNT(ps.P_ID) AS [Male Stations]
FROM
    Agent
    INNER JOIN
    (
        SELECT DISTINCT P_ID
        FROM Polling_Stations
        WHERE Gender = 'Male'
    ) AS ps
    ON Agent.P_ID = ps.P_ID;