it happend in my project when db connection is instable and an item in db is updated twice, does anyone encountered similar situations please?

Use newer go version (Go 1.13 ) and try again.

@syuanyuan708
It's no need to distinguish error types. Driver handles error internally and user does not care about it.
When error occurred in a transaction, call Rollback() and return.

	err := tx.Commit()
	if err != nil {
		tx.Rollback()
		return
	}

@zihengCat
ok, I will try to update Go 1.13 and test it, thanks for your explain.

@zihengCat After reading the code and debugging, I found that after successfully sending "Commit" message to server and failing in receiving response from server(e.g. io timeout), tx.Commit() returns "invalid connection" error, and then tx.Rollback() just do nothing for tx.done==1. So is it possible that commit has been executed in server but indicates a rollback to users?

I think database/sql should provide explicit guideline for this issue.