17. A SQL Visualiser as claimed in claim 1 , wherein said graphical diagram which represents said textual SQL statement comprises graphical blocks of different types, and wherein the relative position of a particular type of said graphical blocks is used to represent different SQL operations.
19. The SQL Visualiser as claimed in claim 17 , wherein said particular type of said graphical blocks is used to represent a “HAVING” construct if said particular type of said graphical blocks is a filter block that is placed after a graphical block that is used to represent a “GROUP BY” construct.