private void ValidationButton_Click(object sender, EventArgs e)
        {
            StringBuilder err  = new StringBuilder();
            Object        data = ValidationClass.isPositiveInteger(textBox1.Text, err);

            if (data == null)
            {
                MessageBox.Show(err.ToString());
            }
            else
            {
                int x = (int)data;
                MessageBox.Show("The entered data is " + x);
            }
        }
 private void getemployeeswithlesssalarybutton_Click(object sender, EventArgs e)
 {
     if (salary_textBox.Text == "")//validation part
     {
         MessageBox.Show("Please, insert a value for base salary.");
     }
     else
     {
         StringBuilder err    = new StringBuilder();
         Object        salary = ValidationClass.isPositiveInteger(salary_textBox.Text, err);
         if (salary == null)
         {
             MessageBox.Show("Salary has an incorrect value " + err.ToString());
         }
         else
         {
             DataTable dt = controllerObj.SelectAllEmployeesWithSalaryLessThan(salary_textBox.Text);
             EmployeeLessSalary_ComboBox.DataSource = dt;
         }
     }
 }
 private void getemployeeswithlesshours_button_Click(object sender, EventArgs e)
 {
     if (hours_textbox.Text == "")//validation part
     {
         MessageBox.Show("Please, insert a value for hours.");
     }
     else
     {
         StringBuilder err   = new StringBuilder();
         Object        hours = ValidationClass.isPositiveInteger(hours_textbox.Text, err);
         if (hours == null)
         {
             MessageBox.Show("Hours has an incorrect value " + err.ToString());
         }
         else
         {
             DataTable dt = controllerObj.GetEmployeesWithLessHours(hours_textbox.Text, deptloc1_comboBox.Text, deptloc2_comboBox.Text);
             EmployeeLessSalary_ComboBox.DataSource = dt;
         }
     }
 }
 private void button1_Click(object sender, EventArgs e)
 {
     if (ProjectName_textBox.Text == "" || ProjectNo_textBox.Text == "" || ProjectLocation_textBox.Text == "")//validation part
     {
         MessageBox.Show("Please, insert all values");
     }
     else
     {
         StringBuilder err = new StringBuilder();
         Object        PNO = ValidationClass.isPositiveInteger(ProjectNo_textBox.Text, err);
         Object        DNO = ValidationClass.isPositiveInteger(DepartmentNo_ComboBox.SelectedValue.ToString(), err);
         if (PNO == null || DNO == null)
         {
             MessageBox.Show("Some inputs has incorrect values " + err.ToString());
         }
         else
         {
             int r = controllerObj.InsertProject(ProjectName_textBox.Text, (int)PNO, ProjectLocation_textBox.Text, (int)DNO);
             MessageBox.Show("Project inserted successfully");
         }
     }
 }
 private void updatesalary_button_Click(object sender, EventArgs e)
 {
     if (ussn_textbox.Text == "" || usalary_textbox.Text == "")//validation part
     {
         MessageBox.Show("Please, insert a value for SSN & New Salary.");
     }
     else
     {
         StringBuilder err    = new StringBuilder();
         Object        ssn    = ValidationClass.isPositiveInteger(ussn_textbox.Text, err);
         Object        salary = ValidationClass.isPositiveInteger(usalary_textbox.Text, err);
         if (ssn == null || salary == null)
         {
             MessageBox.Show("SSN and/or Salary has an incorrect value " + err.ToString());
         }
         else
         {
             DataTable dt = controllerObj.EditSalarybySSN(ussn_textbox.Text, usalary_textbox.Text);
             EmployeeLessSalary_ComboBox.DataSource = dt;
         }
     }
 }
 private void insertdept_button_Click(object sender, EventArgs e)
 {
     if (newdeptmgrstartd_textbox.Text == "" || newdeptmgr_textbox.Text == "" || newdept_textbox.Text == "" || newdno_textbox.Text == "")//validation part
     {
         MessageBox.Show("Please, insert values for required data (new department's name, new dept. ID, newdept. manager's SSN, new dept. manager's start date .");
     }
     else
     {
         StringBuilder err    = new StringBuilder();
         Object        startd = ValidationClass.isPositiveInteger(newdeptmgrstartd_textbox.Text, err);
         Object        dmgr   = ValidationClass.isPositiveInteger(newdeptmgr_textbox.Text, err);
         Object        newd   = ValidationClass.isPositiveInteger(newdept_textbox.Text, err);
         Object        dno    = ValidationClass.isPositiveInteger(newdno_textbox.Text, err);
         if (startd == null || dmgr == null || newd != null || dno == null)
         {
             MessageBox.Show("An entered data has incorrect value " + err.ToString());
         }
         else
         {
             DataTable dt = controllerObj.InsertDept(newdept_textbox.Text, newdno_textbox.Text, newdeptmgr_textbox.Text, newdeptmgrstartd_textbox.Text);
             EmployeeLessSalary_ComboBox.DataSource = dt;
         }
     }
 }