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.

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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

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