Question

There is a table name Top_Up. Its current snapshot is:

When I run query SELECT * FROM Top_Up WHERE Top_up_ID = (round(random() * 9 ) + 1); on it, I am getting random result. Sometimes it is returning with two tuples, sometimes no tuples and sometime one tuple.

To debug I run the query Select (round(random() * 9 ) + 1); and it is always returning only one tuple in the result.

Why I am getting this vague and random result?

Answer 1

Round is being calculated per row. Try this:

SELECT TOP 1 * FROM Top_Up ORDER BY (round(random() * 9 ) + 1);

If you run your test against your table you should see a much different result:

 Select (round(random() * 9 ) + 1) FROM Top_Up `

If you just want a random record I would go with:

SELECT TOP 1 * FROM Top_Up ORDER BY NEWID()