Question

我需要执行一个查询，根据Incidents从表CustomerID获取所有内容。 CustomerID来自MasterAccounts表，该表与Incidents表没有直接关系。有一个SubAccounts表可以INNER JOIN - 用来关联这两个表。

这是我到目前为止所做的：

SELECT
    *
FROM
    MasterAccounts AS ma
INNER JOIN 
    SubAccounts AS sa
INNER JOIN 
    Incidents AS i
WHERE
    ma.CustomerID = sa.CustomerID;
    AND sa.AccountID = i.AccountID
    AND IncidentTypeID = 11;

失败了

关键字＆＃39; WHERE＆＃39;附近的语法不正确。

任何想法都将不胜感激！

Answer 1

您需要在ON之后使用INNER JOIN定义加入条件，以链接这两个表：

SELECT
    *
FROM
    MasterAccounts AS ma
INNER JOIN 
    SubAccounts AS sa ON ma.CustomerID = sa.CustomerID;
INNER JOIN 
    Incidents AS i ON sa.AccountID = i.AccountID
WHERE
    IncidentTypeID = 11;

这些列必须存在于所涉及的表中，并且应具有相同的数据类型（因为否则JOIN可能会导致＆＃34;隐藏＆＃34;数据类型转换，这在性能方面可能代价高昂）

Answer 2

大多数WHERE条件应该在每个连接的ON子句中：

SELECT i.*
FROM MasterAccounts ma
INNER JOIN SubAccounts sa ON sa.CustomerID = ma.CustomerID
INNER JOIN Incidents i ON i.AccountID = sa.AccountID
WHERE IncidentTypeID = 11;

Answer 3

正确的语法是：

SELECT
    *
FROM
    MasterAccounts AS ma
INNER JOIN 
    SubAccounts AS sa ON ma.CustomerID = sa.CustomerID;
INNER JOIN 
    Incidents AS i ON sa.AccountID = i.AccountID
WHERE 
    IncidentTypeID = 11;

希望这有帮助！

具有多个INNER JOIN的

3 个答案: