REPLACE 在内部执行删除然后插入.如果您有指向该行的外键约束，这可能会导致问题.在这种情况下，REPLACE 可能会失败或更糟:如果您的外键设置为级联删除，REPLACE 将导致其他表中的行被删除.即使在 REPLACE 操作之前和之后都满足约束条件，也会发生这种情况.

REPLACE internally performs a delete and then an insert. This can cause problems if you have a foreign key constraint pointing at that row. In this situation the REPLACE could fail or worse: if your foreign key is set to cascade delete, the REPLACE will cause rows from other tables to be deleted. This can happen even though the constraint was satisfied both before and after the REPLACE operation.

使用 INSERT ... ON DUPLICATE KEY UPDATE 可以避免这个问题，因此是首选.

Using INSERT ... ON DUPLICATE KEY UPDATE avoids this problem and is therefore prefered.