public string deleteProfessorToStudent(int pid, string StuID)
{
try
{
SsContext db = new SsContext();
ProfessorToStudent ps = db.ProfessorToStudents.Find(pid, StuID);
ProfessorToStudent pts = new ProfessorToStudent();
List <Professor> plist = db.Professors.Where(s => s.ProID == pid).ToList();
if (plist[0].ProNum > 0)
{
plist[0].ProNum--;
}
if (plist.Count <= 0)
{
return("未知错误");
}
db.ProfessorToStudents.Remove(ps);
db.SaveChanges();
}
catch (Exception e)
{
return("操作失败");
}
return("操作成功");
}
public string addProfessorToStudent(int pid, string StuID)
{
SsContext db = new SsContext();
try
{
ProfessorToStudent pts = new ProfessorToStudent();
List <Professor> plist = db.Professors.Where(s => s.ProID == pid).ToList();
if (plist.Count <= 0)
{
return("未知错误");
}
Professor p = plist[0];
int num = db.ProfessorToStudents.Where(s => s.ProID == pid).ToList().Count;
if (num >= p.ProMaxNum || p.ProNum >= p.ProMaxNum)
{
return("选择学生数已达最大值");
}
if (p.ProNum < p.ProMaxNum)
{
p.ProNum++;
}
pts.ProID = pid;
pts.StuID = StuID;
db.ProfessorToStudents.Add(pts);
db.SaveChanges();
}catch (Exception e)
{
ProfessorToStudent p = db.ProfessorToStudents.Find(pid, StuID);
if (p == null)
{
return("操作失败");
}
else
{
return("操作成功");
}
}
return("操作成功");
}