What I wrote earlier was $row=mysqli_fetch_assoc($result); and an error was reported. If I change it to $row=mysqli_fetch_all(.....) in the article, the ID can be displayed. Aren't these two sentences equivalent? When I wrote it before, foreach could recognize it. What's wrong?

What is the problem with Illegal string offset?-PHP Chinese Network Q&A

What I wrote earlier was $row=mysqli_fetch_assoc($result); and an error was reported. Change it to $row=mysqli_fetch_all(.....) in the article to display the ID. Aren't these two sentences equivalent? When I wrote it before, foreach could recognize it. What's wrong?