MS Access帮助运行查询

Question

我有两个表格如下。

我想获取所有活跃的会员，并且付款周期=每两周一次，以及每个会员在特定年份和月份的相应储蓄记录。请注意，某些成员可能没有给定年份和月份的储蓄记录。 我写了一个查询，但是它不返回在储蓄表中没有储蓄记录的成员。

SELECT Member.memberID As [ID],Member.firstName AS [First Name],
       Member.lastName AS [Last Name], Member.paymentPeriod AS [Payment Period],
       Savings.savingId AS [Savings Id], Savings.enteredAmount AS [Amount]
FROM Member
    LEFT JOIN Savings ON Member.memberID = Savings.memberId
WHERE Member.isActive = 'Active' AND Member.paymentPeriod = 'Fortnightly'
      AND Year(Savings.enteredDate)=2019 AND Month(Savings.enteredDate) = 1;

Answer 1

将SAVINGS条件从WHERE移到ON以获得真实的LEFT JOIN结果：

SELECT Member.memberID As [ID],Member.firstName AS [First Name],
       Member.lastName AS [Last Name], Member.paymentPeriod AS [Payment Period],
       Savings.savingId AS [Savings Id], Savings.enteredAmount AS [Amount]
FROM Member
    LEFT JOIN Savings ON Member.memberID = Savings.memberId
      AND Year(Savings.enteredDate)=2019 AND Month(Savings.enteredDate) = 1
WHERE Member.isActive = 'Active' AND Member.paymentPeriod = 'Fortnightly';

（有了WHERE子句中的条件，您将获得常规的INNER JOIN结果。）

编辑：：尝试避免出现“ 不支持联接表达式错误”：

SELECT Member.memberID As [ID],Member.firstName AS [First Name],
       Member.lastName AS [Last Name], Member.paymentPeriod AS [Payment Period],
       Savings.savingId AS [Savings Id], Savings.enteredAmount AS [Amount]
FROM Member
    LEFT JOIN Savings ON Member.memberID = Savings.memberId
WHERE Member.isActive = 'Active' AND Member.paymentPeriod = 'Fortnightly'
      AND (Year(Savings.enteredDate)=2019 or Year(Savings.enteredDate) IS NULL)
      AND (Month(Savings.enteredDate) = 1 or Month(Savings.enteredDate) IS NULL);