Replacing "(null)" with blank cell in SQL query result

Question

I believe what I'm asking here is possible, but I haven't find a way yet :

Some cells in the result of my SQL SELECT-FROM-WHERE query are blank, and in DbVisualizer, (null) is written inside. I'd like to display a blank cell instead.
I've already tried with CASE-WHEN and the NVL operator, but it won't let me replace it by a blank '', I'm forced to use some ' ' or 'message'.

I know I could just delete these spaces or messages with Excel later, but I'd like to know if there is a way to do it directly with DbVisualizer, instead of this workaround.

---

EDIT: Here is what my request looks like :

SELECT *things*,
  CASE WHEN
     (SELECT COUNT(*) FROM table d2 WHERE *join-condition* AND *other condition*) = 1
  THEN
     (*sub-select query*)
  ELSE
     ''
  END
  AS NAME,
  *other things*
  FROM table d1
  WHERE *something*

Thanks a lot !

Answer 1

Did you try standard SQL function coalesce(), as below ?

SELECT COALESCE(columnName, '') AS ColumnName FROM tableName;

---

Syntax:

COALESCE (expr1, expr2)

is equivalent to:

CASE WHEN expr1 IS NOT NULL THEN expr1 ELSE expr2 END

Similarly,

COALESCE (expr1, expr2, ..., exprn), for n>=3

is equivalent to:

CASE WHEN expr1 IS NOT NULL THEN expr1 
   ELSE COALESCE (expr2, ..., exprn) END

Above examples are from Database SQL Language Reference