title: Query with empty or one row only
body: <p>I'm using an oracle DB and I need to know if certain value is on myTable (it can be 0-N times), but i'm using a software that does some tasks with each row of the query output, so, my result should be empty when I have no value in myTable (so the software will do nothing) or one row when I have 1 or more values in myTable (so the software will do what it needs to do one time only). My problem is:</p>
  <p>If I use: <code>SELECT 1 FROM myTable WHERE col = value</code> it returns empty for 0 values, but return N for N values and the sofware runs N times when it should only run once.</p>
  <p>If I use: <code>SELECT max(1) FROM myTable WHERE col = value</code> it returns 1 row for N values, but it also returns 1 row for 0 values (in this case the row has NULL, but still trigger my software to do the tasks that should be done only with 1 or more values).</p>
  <p>Someone know how can I make a single query that return empty for 0 values and 1 row for N values? Thanks.</p>