title: Selecting the columns which are not null from a tuple
body: <p>Imagine if we have a table: <br></p>
  
  <pre>| col1 | val1 | val2 | val3 | val4 | val5 |
  -------------------------------------------
  | A    |   1  | null | null | null |   1  |
  | B    | null |   1  | null |   1  | null |
  | C    |    1 | null |   1  | null | null |</pre>
  
  <p>and can i write an SQL query to give me a the following result, where i can get the columns which are not null :</p>
  
  <pre>| col1 | val1 | val5 |
  ----------------------
  | A    |   1  |   1  |</pre>
  
  <p>rather than using a separate function to do the same? </p>