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"); }