Students(sid, name, degree, ...)
// e.g. Students(3322111, 'John Smith', 'MEngSc', ...)
Courses(cid, code, term, title, ...)
// e.g. Courses(1732, 'COMP9311', '12s1', 'Databases', ...)
Enrolments(sid, cid, mark, grade)
// e.g. Enrolments(3322111, 1732, 50, 'PS')

select s.sid, s.name, e.mark
from Students s join Enrolments e on s.sid = e.sid
                join Courses c on e.cid = c.cid
where c.code = "COMP9315" and c.term = '18s2'

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

void giveUp(char *);

int main(int argc, char **argv) {
    char *buf;
    int inf;
    int bufsize;
    ssize_t nread;
    int nblocks = 0, nbytes = 0;

    // process command line args
    if (argc < 3) giveUp("Insufficient args");
    bufsize = atoi(argv[1]);
    if (bufsize < 100) giveUp("Invalid buffer size");
    buf = malloc(bufsize * sizeof(char));
    if (buf == NULL) giveUp("Can't create buffer");

    // open file
    if ((inf = open(argv[2], O_RDONLY)) < 0) {
        giveUp("Can't read file");
    }

    // read file and count blocks/bytes
    while ((nread = read(inf, buf, bufsize)) != 0) {
        nblocks ++;
        nbytes += nread;
        printf("%ld bytes read in current block\n", nread);
    }

    // display results
    printf("Read %d blocks and %ld bytes\n", nblocks, nbytes);

    exit(EXIT_SUCCESS);
}

void giveUp(char *msg) {
    fprinf(stderr, "Error: %s\n", msg);
    fprinf(stderr, "Usage: ./blocks Blocksize InputFile\n");
    exit(EXIT_FAILURE);
}