IF() problem

[Przemyslaw Popielarski]

select IF(BOOK1PL,BOOK1PL,BOOK1EN)
from tBooksextra where ksi='id'

-> (content of BOOK1EN)

select BOOK1PL from tBooksextra 
WHERE BOOK1PL IS NOT NULL
AND  BOOK1PL!='' AND ksi='id'

-> (content of BOOK1PL).


Why didn't I get the content of BOOK1PL in 1st query?

(checked in 4.0.21 and 4.1.7)

./ premax
./ premax@stripped
./ koniec i bomba, a kto czytal ten traba. w.g.