Contents
• Adding a new record into database• Changing an existing record• Deleting a record• Displaying data from multiple tables
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3. Writing the Program
a) Adding database file into solutionb) Displaying studentsc) Adding new studentd) Changing student infoe) Deleting a studentf) Displaying all courses a student take
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Create a New Form “frmNewStudent”
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tbFirstName
tbLastName
calBirthDay
numAge
btnOK withDialogResult = OK
btnCancel withDialogResult = Cancel
Double-Click OK Button and Write the Following Code
studentsTableAdapter1.Insert(tbFirstName.Text,tbLastName.Text,calBirthDay.Value,(short)numAge.Value);
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Double-Click the Button and Write the Following Code:
frmNewStudent frm = new frmNewStudent();DialogResult result = frm.ShowDialog();if (result == DialogResult.OK){ studentsTableAdapter.Fill( schoolDataSet.Students);}
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Some Notes
• If you close your application, make some changes in your program, build the program again, and execute the program, the last added records won’t be visible!
• This is because each time you build the project, original database file is copied into the Debug folder in your solution and all operations are made on this copy.
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Binding Data to the Controls
• In order to fill the controls, we are going to use data binding feature instead of changing contents of the controls.
• The frmChangeStudent form needs the StudentID to display the data of the selected student.
• For this purpose, create a property in frmChangeStudent form. This property will transfer student ID from main form to frmChangeStudent form.
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“FillByStudentID” instead of “Fill”
• We want to display the data of only one student.
• So, we need to use FillByStudentID method instead of Fill method.
• Delete the line and write this:this.studentsTableAdapter.FillByStudentID(
this.schoolDataSet.Students,this.StudentID);
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OK Button
• When the form is displayed, the data of the student is displayed on the controls.
• User changes these data and presses OK button.
• So, we need to write updating code into the Click event of the OK button.
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Updating to Database
• The modifications made by the user must be applied to the data set. This is accomplished by the EndEdit() method of the BindingSource object.
• The changes on the data set is applied to the database by the Update() method of the studentTableAdapter object.
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OK Button Click Event
• Double-click the OK button and write this code:
this.studentsBindingSource.EndEdit();this.studentsTableAdapter.Update(
this.schoolDataSet.Students);
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Passing Student ID
• Now, the form can display and update the data of the student whose ID is specified by the StudentID property.
• So, we need to set this property before the form is shown.
• This should be done in the main form.
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Getting the ID of the selected student
• The ID of the student selected from the DataGridView object can be obtained in two ways:
1. Get the ID from the first cell of the selected row or the DataGridView.
2. Get the ID from the binding source object.
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1. Getting ID from DataGridView
int studentID =(int)dataGridView1.SelectedRows[0].Cells[0].Value;
• In order this code to be successfully executed, you need to set MultiSelect property of the DataGridView object to False and SelectionMode property to FullRowSelect.
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2. Getting ID from Binding Source
• When a row is selected in the DataGridView object, the information about the selected row is stored in binding source object. You can get the StudentID by using this code:
DataRowView rowView = (DataRowView)studentsBindingSource.Current;
SchoolDataSet.StudentsRow row = (SchoolDataSet.StudentsRow)rowView.Row;
int studentID = row.StudentID;43
Creating the frmChangeStudent dialog and passing student ID
• Add a new button with the text “Change Student Info” into the main form.
• Write the code given in the next slide into the Click event handler of the button.
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DataRowView rowView = (DataRowView)studentsBindingSource.Current;
SchoolDataSet.StudentsRow row = (SchoolDataSet.StudentsRow)rowView.Row;
int studentID = row.StudentID;
frmChangeStudent frm = new frmChangeStudent();frm.StudentID = studentID;DialogResult result = frm.ShowDialog();
if (result == DialogResult.OK){ // Update the DataGridView: this.studentsTableAdapter.Fill(this.schoolDataSet.Students);}
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Double-click the button and write the following code:
// Get the selected row:DataRowView rowView =
(DataRowView)studentsBindingSource.Current;SchoolDataSet.StudentsRow row =
(SchoolDataSet.StudentsRow)rowView.Row;
// Delete the student:this.studentsTableAdapter.Delete(row.StudentID, row.FirstName,
row.LastName, row.BirthDay, row.Age);
// Update DataGridView:this.studentsTableAdapter.Fill(schoolDataSet.Students);
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