Question

我有4个子查询需要作为一个单元运行，并在1个列表中检索不同的结果。我的java应用程序将使用Spring Data JPA存储库调用此查询，它应该返回一个List。

## S_NAME based on TABLE_1.Id = 1
SELECT DISTINCT(S_NAME) FROM TABLE_1 WHERE S_ID = 1;

## I_NAME based on TABLE_1.Id = 1
SELECT DISTINCT(I_NAME) FROM I_TABLE WHERE I_ID
IN (SELECT I_ID FROM E_TABLE WHERE S_ID = 1);

## C_NAME based on TABLE_1.Id = 1
SELECT DISTINCT(C_NAME) FROM C_TABLE WHERE C_ID
IN (SELECT C_ID FROM C_TABLE WHERE E_ID
IN (SELECT E_ID FROM E_TABLE WHERE S_ID = 1));

## P_NAME based on TABLE_1.Id = 1
SELECT DISTINCT(P_NAME) FROM P_TABLE WHERE C_ID
IN (SELECT C_ID FROM C_TABLE WHERE E_ID
IN (SELECT E_ID FROM E_TABLE WHERE S_ID = 1));

S_NAME，I_NAME，C_NAME和P_NAME列包含相同的数据。只是不同的名称，所以我们知道该数据的来源。但是，对于此查询，我需要来自1列中所有这些列的不同结果。

这可以在不进行存储过程的情况下轻松完成吗？我愿意，但我没有这种东西的授权。制作视图时的相同构造。

Answer 1

您可以使用union all获取行中的值或将它们放在不同的列中。这是一种方式：

SELECT (SELECT DISTINCT(S_NAME) FROM TABLE_1 WHERE S_ID = 1
       ) as val1,
       (SELECT DISTINCT(I_NAME) FROM I_TABLE WHERE I_ID IN (SELECT I_ID FROM E_TABLE WHERE S_ID = 1
       ) as val2,
       (SELECT DISTINCT(C_NAME) FROM C_TABLE
        WHERE C_ID IN (SELECT C_ID FROM C_TABLE WHERE E_ID IN (SELECT E_ID FROM E_TABLE WHERE S_ID = 1))
       ) as val3,
       (SELECT DISTINCT(P_NAME) FROM P_TABLE
        WHERE C_ID IN (SELECT C_ID FROM C_TABLE WHERE E_ID IN (SELECT E_ID FROM E_TABLE WHERE S_ID = 1))
       ) as val4;

虽然查询类似，但我不确定是否值得尝试将它们合并。

Answer 2

使用UNION，这意味着render partial: @article, locals: { full: true }，因此您无需这样说：

render @article, full: true

仅供参考：第三个查询是双读DISTINCT，这是一种浪费。我把它放在一边，假设设置这个例子是一个简单的错误。

Answer 3

SELECT (S_NAME) FROM TABLE_1 WHERE S_ID = 1;

UNION
SELECT (I_NAME) FROM I_TABLE WHERE I_ID
IN (SELECT I_ID FROM E_TABLE WHERE S_ID = 1);

UNION
SELECT (C_NAME) FROM C_TABLE WHERE C_ID
IN (SELECT C_ID FROM C_TABLE WHERE E_ID
IN (SELECT E_ID FROM E_TABLE WHERE S_ID = 1));
-- HERE UNION will only Take DISTINCT row from the each query no need of Distinct
UNION
SELECT (P_NAME) FROM P_TABLE WHERE C_ID
IN (SELECT C_ID FROM C_TABLE WHERE E_ID
IN (SELECT E_ID FROM E_TABLE WHERE S_ID = 1));

在非直接关联的表上的子查询中组合SQL中的列

3 个答案: