Question

In Mysql there is a compare operator that is a null safe: <=>. I use this in my Java program when creating prepared statements like this:

String routerAddress = getSomeValue();
String sql = "SELECT * FROM ROUTERS WHERE ROUTER_ADDRESS <=> ? ";
PreparedStatement stmt = connection.prepareStatement(sql);
stmt.setString(1, routerAddress);

Now I would like to switch to the H2 database. How do I write the <=> operator in pure SQL (using for example IS NULL and IS NOT NULL)? I would like use the stmt.setString operation only once. It is okay to write the column name several times.

Related question is Get null == null in SQL. But that answer requires the search value to be written 2 times (that is: 2 question marks in my PreparedStatement)!?

Reference:
http://dev.mysql.com/doc/refman/5.0/en/comparison-operators.html#operator_equal-to

Answer 1

Related question is Get null == null in SQL. But that answer requires the search value to be written 2 times (that is: 2 question marks in my PreparedStatement)!?

The second-ranked and subsequent answers give a method to do this without binding the search value twice:

SELECT * FROM ROUTERS 
WHERE coalesce(ROUTER_ADDRESS, '') = coalesce( ?, '');

Note that this requires a dummy value that can never be valid column value (that’s “out of band”); I’m using the empty string. If you don’t have any such value, you’ll have to put up with binding the value twice:

SELECT * FROM ROUTERS 
WHERE ROUTER_ADDRESS = ? or (ROUTER_ADDRESS is null and ? is null);