I remember one interview I had with a candidate. It was for a database analyst position that required SQL.
The first round was typically a phone screen where I chat with the candidate, get to know them a bit.
Second round was code review. I asked them to do a SQL query that did x.
The queries were simple. The goal was to get the candidate to walk through the query.
I had one candid that, over screen share, wrote the query flawlessly. Then I asked them to explain what it was doing. The candidate froze.
I can get understand getting nervous so I moved onto an insert statement. I had them write one and then do another without using certain terms (often leading to a sub query).
Again, flawless. I asked what situations would you use one over the other.
Again, they froze. I started to get suspicious that they were cheating and had them, instead of typing the answer, say the answer. When they couldn't, I knew enough that it wasn't going to work.