Which MySQL Statement Fails: SELECT 1, 2, 3 vs SELECT 1 2 3 vs SELECT '1 2 3'

An online assessment includes this multiple-choice question. Each option is a complete statement run on its own in MySQL. Select the expression that causes a MySQL error. - **A.** `SELECT 1, 2, 3` - **B.** `SELECT 1 2 3` - **C.** `SELECT '1 2 3'` - **D.** None of the above; all expressions are correct. Choose one option, and explain what MySQL does with each of the others. ```hint What may follow a value Once the parser has read a complete value after `SELECT`, ask which kinds of token it can accept next. ``` ```hint Inside and outside quotes Compare what the parser sees between quotation marks with what it sees without them. ``` ### Clarifying Questions - Is each option executed by itself, with no `FROM` clause and no surrounding statement? - Does "causes an error" mean the server rejects the statement, as opposed to running it with a warning or an unexpected result? - Should MySQL's default SQL mode be assumed, or a mode such as `ANSI_QUOTES` that changes how quotation marks are read? ### What a Strong Answer Covers - The failing option, with the parsing reason it fails rather than a guess - What options A and C each return: how many columns, and what values - Why "none of the above" is wrong - How MySQL's optional `AS` keyword decides which missing-comma mistakes fail and which run silently ### Follow-up Questions - `SELECT price quantity FROM orders` runs without an error. What does it return, and why is that harder to catch than option B? - What do `SELECT 1 'total'` and `SELECT '1' '2' '3'` return in MySQL? - Would option B also fail in PostgreSQL, and how do the two statements in the previous follow-up behave there?