> "even numeric data" is imported as text Column types in Sqlite are not strictly enforced. If you import data that 'look' numeric from your text file into a column with a numeric type, the data will be stored in a numeric format; if a particular value cannot be converted to a numeric format, it will be stored as text -- so you may have '' in a numeric column where you want a null. See <www.sqlite.org/datatype3.html> for a more rigorous explanation.
BTW, you shouldn't have to type individual update statements for each column. Sqlite is usable from almost all scripting languages. For example, in tcl if you get the column names into a variable called columns, you can do something like load tclsqlite3.so sqlite dbcmd filename.db dbcmd eval {begin exclusive} foreach c $columns { dbcmd eval {upate table set $c=null where $c=''} } dbcmd eval commit dbcmd close Regards