我如何在不使用联接的情况下重写查询 [英] How could I rewrite a query without using joins

问题描述

我想知道如果不使用任何联接将如何编写此查询.我一直在尝试找出联接不可行或无法使用(无法使用)的情况.

I would like to know how this query would be written if no joins were used. I been trying to figure it out for cases where joins aren't viable or can't be used(aren't available).

SELECT
    *
FROM
(
    table1
INNER JOIN
    table2
ON
    table1.id = table2.id
)
INNER JOIN
    table3
ON
(
    table1.id2 = table3.id2
)
AND
(
    table1.id3 = table3.id3
)
WHERE
    table1.id = 1

我不能使用联接的原因是因为应用程序使用HQL而不是标准SQL，并且HQL使得联接非常困难.

The reason I can't use joins is because the application uses HQL as opposed to standard SQL and HQL makes joins incredibly difficult to do.

推荐答案

如果不以一种或另一种方式联接它们，就不可能从两个不同的表中提取数据.您正在使用JOIN语句，但是可以通过将其放置在where子句中来实现相同的目的，例如:

It is impossible to extract data from two different tables without joining them in one way or another. You are using a JOIN statement BUT you can achieve the same thing by placing it in the where clause for example:

SELECT * FROM table1, table2 WHERE table1.id = table2.id AND ...

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