OSX-NSTableview reloadData method do not load data from sqlite properly

I'm new to objective-c programming. I'm doing an application to manage data from a sqlite database. It's used to check attendance of students.

As I'v implemented the update button which change registration time of a student, I used reloadData method to refresh the tableview. However, it doesn't work properly. It did change the view, but not the right cell.

For example, I tried to change the registration time of student A, the method change that of student B.

I debugged it, the database was updated correctly, so I think it is the method wrong. Can anyone give me a hint on the problem? Any suggestion will be appreciated :)

    if ([[self.StartOrEndMatrix.selectedCell title] isEqualToString:@"上课"]) {
        changedColumn = 3;
    }else if([[self.StartOrEndMatrix.selectedCell title] isEqualToString:@"下课"]){
        changedColumn = 4;
    }

    if ([[self.NameOrNumberMatrix.selectedCell title] isEqualToString:@"按姓名"]) {
        Index = 1;
    }else if ([[self.NameOrNumberMatrix.selectedCell title] isEqualToString:@"按学号"]){
        Index = 0;
    }

    NSString* whereString = [[NSString alloc] initWithString:[self.RegistraitionTextField stringValue]];
    NSString* data = [self presentTime];

    [self updateStudentInSqlite:_database table:self.table atChangedColumn:changedColumn withOriginValue:whereString atIndex:Index andNewString:data];

    [self updateColumnArrayNamed:self.attributeNameArray[changedColumn] atIndex:changedColumn withValue:data];

    [self fullDataToStudentInTable];
    [self.InfoTable reloadData];