Say I have a table named "ONE" with a single column "Column1." Let the data be as below:
Column1 ------- a b c
What will be the query to display the three records concatenated into a single row? I was unable to answer this question in an interview!! Thanks in advance.
What kind of a question is that?? The interviewer was clearly trying to rattle you, because that's a pretty dumb question. I would have been tempted to reply "The answer is available by inspection -- 'a,b,c'. Voila and QED. I don't write queries for trivialities. Now please ask me something serious, like the difference between surrogate and natural keys."
Okay, let's look at some solutions. Here's the answer in MySQL:
select group_concat(Column1) from ONE
Here's the answer in Sybase ASA:
select list(Column1) from ONE
If you're using any other database system, it gets a little harder. In Oracle, you can try some of these methods. Other databases require similar approaches.
This was first published in June 2006