i get this error while compiling my .o file (object file)

Data.c:24: error: field `HtStatus' has incomplete type
Data.c:25: error: field `DcStatus' has incomplete type

struct database {
    struct hStat HtStatus[SIZE];
    struct dStat DcStatus; 
 };

 struct hStat {
//something;
};

 struct dStat {
//something;
};

do i need to use typedef to those structure (dStat, hStat)?

You are using the structures before even declaring or defining them. Make the definition of the two structures hStat and dStat precede the definition of Database and it should go allright.

Also if you have not done "#define SIZE 100" or any other constant value it will flag an error.