(1) attempt to execute a program that does not compile correctly. Most compilers nowdays do not produce the executable when there are compile errors, but I have seen a few compilers do that in the past.
(2) buffer overruns
(3) using uninitialized pointers
(4) dereference NULL pointers
(5) attempt to address memory the program does now own.
(6) failure to check for data validity before using it.
(7) faileure to check for file open success before attempting to use the file pointer.
>>my main prob.. is i can't completely compile my program..
ahmm.. it can't find my database..
Those are two unrelated questions. Please post code that will not compile and post the error messages.
What kind of database are you using? What compiler? What operating system? Is the database in the location you told your program that it is in?