Question

我有一个包含列的表：借记，贷记，借记平衡，信用余额和金额。借方和贷方均与特定账户有关。

每次添加新行时，我都希望根据帐户之前的余额分配debit_balance和credit_balance。

INSERT INTO `ledger` (`debit`, `credit`, `debit_balance`, `credit_balance`, `amount`) 
VALUES ('1', '3', 
(SELECT debit_balance FROM `ledger` WHERE `debit` = '1' ORDER BY `id` DESC LIMIT 0,1) + 5, 
(SELECT credit_balance FROM `ledger` WHERE `credit` = '3' ORDER BY `id` DESC LIMIT 0,1) + 5,
'5')

如果借记卡的帐户为1，则信用卡的帐户为3，我想要更改的金额为5。

当我运行查询时，mysql给出了Every derived table must have its own alias错误。

Answer 1

您可以使用单个SELECT查询来提供要插入的值。

INSERT INTO ledger (debit, credit, debit_balance, credit_balance, amount)
SELECT 1, 3, l1.debit_balance + 5, l2.credit_balance + 5, 5
FROM (SELECT MAX(id) AS debit_id FROM ledger WHERE debit = 1) AS maxd
JOIN ledger AS l1 ON l1.id = maxd.debit_id
CROSS JOIN (SELECT MAX(id) AS credit_id FROM ledger WHERE credit = 3) AS maxc
JOIN ledger AS l2 ON l2.id = maxc.credit_id

mysql：基于另外两行的值运行插入

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