Tablealias as column qualifier in resultset

[Per Newgro]

Hi,

i've a little question. 
If i execute the example-statement
  
  SELECT MYTABLE.* FROM myTable MYTABLE WHERE MYTABLE:A = 5;

i expected to access the column in resultset by usage of

  Object o = getObject("MYTABLE.A);

But this is throwing a ColumnNotFoundException. The other access is working.

  Object o = getObject("A);

I'm a little bit confused because how is derby solving same column names in a 
join of two tables, if the columns are not referenced by the qualifier?

Cheers
Per