mysql - EXISTS IN 查询如何？

Question

有人可以帮我吗，我有 2 张桌子

财务账户货币映射和自有账户。

我想选择字段 legalEntity_id 的金融账户货币映射。

这是我到目前为止所拥有的。

SELECT 
FROM financeaccountcurrencymapping 
WHERE ownedAccount_id EXISTS IN (
                SELECT id 
                FROM ownedaccount 
                WHERE legalEntity_id = ??);

表中的字段是：

'财务账户货币映射'

• ID
• 货币货币
• accountForCash_id
• 拥有的Account_id

'自有帐户'

• ID
• 姓名
• legalEntity_id
• 资产或负债
• 资产类型
• 存款类型
• 责任类型
• 多种货币
• 货币
• 描述

Answer 1

在这种情况下，您不会使用 EXISTS。单独的 IN 就可以了。

SELECT 
FROM financeaccountcurrencymapping 
WHERE ownedAccount_id IN (SELECT id FROM ownedaccount WHERE legalEntity_id = ??);

Answer 2

You're original query is really close. You just need to remove the EXISTS, like so:

SELECT *
FROM financeaccountcurrencymapping 
WHERE ownedAccount_id IN (
                SELECT id 
                FROM ownedaccount 
                WHERE legalEntity_id = ??);

Alternatively, you could write this query with a JOIN for the same effective result.

SELECT f.*
FROM financeaccountcurrencymapping AS f 
INNER JOIN ownedaccount AS o ON (f.id = o.ownedAccount_id) 
WHERE o.legalEntity_id = ??;

Answer 3

如果您真的想使用 EXISTS 或想查看如何使用它的示例，我认为以下内容会起作用。就个人而言，我可能会使用 IN 代替。

SELECT 
FROM financeaccountcurrencymapping as f
WHERE EXISTS (SELECT id 
              FROM ownedaccount 
              WHERE f.ownedAccount_id = id AND legalEntity_id = ??);

Answer 4

SELECT legalEntity_id
FROM financeaccountcurrencymapping 
WHERE ownedAccount_id IN (
                SELECT id 
                FROM ownedaccount 
                WHERE legalEntity_id = ??);