Question

我有一个像下面这样的查询工作正常。

SELECT 
    "A".id AS A_id,
    "B".id AS B_id,
    "C".id AS C_id,
    "D".id AS D_id,
    "E".id AS E_id,
    "F".id AS F_id,
    "G".id AS G_id,
    "H".id AS H_id,
    "I".id AS I_id
FROM "A" 
INNER JOIN "B" ON "A".id = "B".A_id 
INNER JOIN "C" ON "B".C_id = "C".id
INNER JOIN "D" ON "C".D_id = "D".id
INNER JOIN "E" ON "D".id = "E".D_id
INNER JOIN "F" ON "E".F_id = "F".id
INNER JOIN "G" ON "F".G_id = "G".id
INNER JOIN "H" ON "G".id = "H".G_id
INNER JOIN "I" ON "H".I_id = "I".id;

现在我想添加特殊条件。表＆＃34; B＆＃34;与另一个表连接而且我必须添加特殊连接（完全连接）但是在所有连接之后。像下面的东西（它当然不起作用）：

SELECT 
    "A".id AS A_id,
    "B".id AS B_id,
    "C".id AS C_id,
    "D".id AS D_id,
    "E".id AS E_id,
    "F".id AS F_id,
    "G".id AS G_id,
    "H".id AS H_id,
    "I".id AS I_id,
    "Setup".id AS setup_id,
    "Run".id AS run_id
FROM "A" 
INNER JOIN "B" ON "A".id = "B".A_id 
INNER JOIN "C" ON "B".C_id = "C".id
INNER JOIN "D" ON "C".D_id = "D".id
INNER JOIN "E" ON "D".id = "E".D_id
INNER JOIN "F" ON "E".F_id = "F".id
INNER JOIN "G" ON "F".G_id = "G".id
INNER JOIN "H" ON "G".id = "H".G_id
INNER JOIN "I" ON "H".I_id = "I".id

AND FROM
"Setup" 
FULL JOIN "Run" ON "Setup".id = "Run".id
FULL JOIN "B" ON "Setup".id = "B".id;

我使用完全加入，因为每个表＆＃34;运行＆＃34;和＆＃34;设置＆＃34;仅包含一行，但与表格相关联＆＃34; B＆＃34;它有更多的那一行，我想把它们全部放在结果表中。

如何修复？也许尝试在select中使用select？

Answer 1

您不需要完全加入即可在您描述的1对多关系中反映多行。另一个内部联接。并且没有＆＃34; AND FROM＆＃34;施工。您可以直接添加联接。

INNER JOIN "I" ON "H".I_id = "I".id
INNER JOIN "Setup" ON "B".id = "Setup".id;
INNER JOIN "Run" ON "Setup".id = "Run".id

您应该阅读joins。

[编辑]

注释表明数据是不对称的，因此您需要外连接，因此：

INNER JOIN "I" ON "H".I_id = "I".id
LEFT JOIN "Setup" ON "B".id = "Setup".id;
LEFT JOIN "Run" ON "Setup".id = "Run".id

在sql查询中的同一个表上使用两个JOIN

1 个答案: