How do i get the Update operation working in this C# CRUD ?

Question

In this C# CRUD. Only the Update function is not working at all while the Add, Clear and Delete are working as planed. What do i need to edit to the code to get the Update class to work as planed? Source code see the .zipfile or see below. using AContact.AContactClasses; using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Windows.Forms; namespace AContact { public partial class AContact : Form { public AContact() { InitializeComponent(); } ContactClass c = new ContactClass(); private void BtnAdd_Click( object sender, EventArgs e) { // Get the value from the input fields c.FirstName = tbFirstName.Text; c.LastName = tbLastName.Text; c.Phone = tbPhone.Text; c.Email = tbEmail.Text; c.Note = tbNote.Text; c.Status = cmbStatus.Text; // Inserting datat into database bool success = c.Insert(c); if (success == true ) { // succesfully Inserted MessageBox.Show( "New contact succesfully inserted" ); // Call the Clear method here Clear(); } else { // Faild to add contact MessageBox.Show( "Failed to add new contact. Try again." ); } // load data on Gridview DataTable dt = c.Select(); dgvContactList.DataSource = dt; } private void AContact_Load( object sender, EventArgs e) { // load data on Gridview DataTable dt = c.Select(); dgvContactList.DataSource = dt; } // Method to clear fields public void Clear() { tbFirstName.Text = "" ; tbLastName.Text = "" ; tbPhone.Text = "" ; tbEmail.Text = "" ; tbNote.Text = "" ; cmbStatus.Text = "" ; } private void BtnUpdate_Click( object sender, EventArgs e) { // Get the data from textboxes c.ContactID = int .Parse(tbContactID.Text); c.FirstName = tbFirstName.Text; c.LastName = tbLastName.Text; c.Phone = tbPhone.Text; c.Email = tbEmail.Text; c.Note = tbNote.Text; c.Status = cmbStatus.Text; // Update data in database bool success = c.Update(c); if (success== true ) { // Updated succesfully MessageBox.Show( "Contact has been succesfully Updated" ); // Load data on Data Gridview DataTable dt = c.Select(); dgvContactList.DataSource = dt; // Call Clear Method Clear(); } else { // Failed to Update MessageBox.Show( "Failed to update. Try again." ); } } private void BtnDelete_Click( object sender, EventArgs e) { c.ContactID = Convert.ToInt32(tbContactID.Text); bool success = c.Delete(c); if (success == true ) { // Succesfully deleted MessageBox.Show( "Contact succesfully deleted." ); // Refresh data GridView // Load Data on Data GridView DataTable dt = c.Select(); dgvContactList.DataSource = dt; // Call the Clear methode here Clear(); } else { // Failed to delete MessageBox.Show( "Failed to delete contact. Try again." ); } } private void BtnClear_Click( object sender, EventArgs e) { // Call Clear method here Clear(); } private void dgvContactList_RowHeaderMouseClick( object sender, DataGridViewCellMouseEventArgs e) { // Get data from Data Grid View and load it to the textboxes respectively // Identify the row on witch mouse is clicked int rowIndex = e.RowIndex; tbContactID.Text = dgvContactList.Rows[rowIndex].Cells[0].Value.ToString(); tbFirstName.Text = dgvContactList.Rows[rowIndex].Cells[1].Value.ToString(); tbLastName.Text = dgvContactList.Rows[rowIndex].Cells[2].Value.ToString(); tbPhone.Text = dgvContactList.Rows[rowIndex].Cells[3].Value.ToString(); tbEmail.Text = dgvContactList.Rows[rowIndex].Cells[4].Value.ToString(); tbNote.Text = dgvContactList.Rows[rowIndex].Cells[5].Value.ToString(); cmbStatus.Text = dgvContactList.Rows[rowIndex].Cells[6].Value.ToString(); } } } ContactClass.cs using System; using System.Collections.Generic; using System.Data; using System.Data.SqlClient; using System.Configuration; using System.Linq; using System.Text; using System.Threading.Tasks; namespace AContact.AContactClasses { class ContactClass { // Getter and Setters properties // Acts as a data carrier in this application public int ContactID { get ; set ; } public string FirstName { get ; set ; } public string LastName { get ; set ; } public string Phone { get ; set ; } public string Email { get ; set ; } public string Note { get ; set ; } public string Status { get ; set ; } static string myconnstrng = ConfigurationManager.ConnectionStrings[ "connstrng" ].ConnectionString; // Selecting data from database public DataTable Select() { // step 1: Database connection SqlConnection conn = new SqlConnection(myconnstrng); DataTable dt = new DataTable(); try { // step 2: Writing sql query string sql = "SELECT * FROM tbl_contact" ; // Creating cmd using sql and conn SqlCommand cmd = new SqlCommand(sql, conn); // Creating sql DataAdappter using cmd SqlDataAdapter adapter = new SqlDataAdapter(cmd); conn.Open(); adapter.Fill(dt); } catch (Exception ex) { } finally { conn.Close(); } return dt; } // Inserting into database public bool Insert(ContactClass c) { // Creating a default returntype and setting its value to false bool isSuccess = false ; // Step 1. Connect database SqlConnection conn = new SqlConnection(myconnstrng); try { // Step 2: Create a SQL query to insert data string sql = "INSERT INTO tbl_contact (FirstName, LastName, Phone, Email, Note, Status) VALUES(@FirstName, @LastName, @Phone, @Email, @Note, @Status)" ; // Creating SQL Command using sql and conn SqlCommand cmd = new SqlCommand(sql, conn); // Create Parameters to add data cmd.Parameters.AddWithValue( "@FirstName" , c.FirstName); cmd.Parameters.AddWithValue( "@LastName" , c.LastName); cmd.Parameters.AddWithValue( "@Phone" , c.Phone); cmd.Parameters.AddWithValue( "@Email" , c.Email); cmd.Parameters.AddWithValue( "@Note" , c.Note); cmd.Parameters.AddWithValue( "@Status" , c.Status); // Connection Open here conn.Open(); int rows = cmd.ExecuteNonQuery(); // If the query runs succesfully then the value is > 0, else the value will be if (rows > 0) { isSuccess = true ; } else { isSuccess = false ; } } catch (Exception ex) { } finally { conn.Close(); } return isSuccess; } // Method to update data in database public bool Update(ContactClass c) { // Create a default return type and set its default value to false bool isSuccess = false ; SqlConnection conn = new SqlConnection(myconnstrng); try { // SQL to update data in hour database string sql = "UPDATE tbl_contact SET FirstName=@FirstName, LastName=@LastName, Phone=@Phone, Email=@Email, Note=@Note, Status=@Status WHERE ContactID=@ContactID" ; // Creating SQL command SqlCommand cmd = new SqlCommand(sql, conn); // Create Parameters to add value cmd.Parameters.AddWithValue( "@FirstName" , c.FirstName); cmd.Parameters.AddWithValue( "@FirstName" , c.LastName); cmd.Parameters.AddWithValue( "@Phone" , c.Phone); cmd.Parameters.AddWithValue( "@Email" , c.Email); cmd.Parameters.AddWithValue( "@Note" , c.Note); cmd.Parameters.AddWithValue( "@Status" , c.Status); cmd.Parameters.AddWithValue( "@ContactID" , c.ContactID); // Open database connection conn.Open(); int rows = cmd.ExecuteNonQuery(); // If the query runs succesfully then the value of rows > 0 else its value will be 0 if (rows > 0) { isSuccess = true ; } else { isSuccess = false ; } } catch (Exception ex) { } finally { conn.Close(); } return isSuccess; } // Method to delete data from database public bool Delete(ContactClass c) { // create a default return value and set its value to false bool isSuccess = false ; // Create SQL Connection SqlConnection conn = new SqlConnection(myconnstrng); try { // Method to delete data string sql = "DELETE FROM tbl_contact WHERE ContactID=@ContactID" ; // Creating SQL command SqlCommand cmd = new SqlCommand(sql, conn); cmd.Parameters.AddWithValue( "@ContactID" , c.ContactID); // Open Connection conn.Open(); int rows = cmd.ExecuteNonQuery(); // if the query runs succesfully then the value of rows will be > 0 , else the value will be 0 if (rows > 0) { isSuccess = true ; } else { isSuccess = false ; } } catch (Exception ex) { } finally { // Close connection conn.Close(); } return isSuccess; } } }

Nitin Sontakke · Answer

Real stupid copy paste error virtually every developer does at least once in his / her career. In your code listing above, see line number 114. It should have been @LastName. You simply have ignored the exceptions you have handled. You must log it to the file (check log4net, for example). That way you could have identified it yourself. Or could have put break point at the catch block of your code. Few suggestions: Instead of: if (rows > 0) { isSuccess = true ; } else { isSuccess = false ; } Just say, as follows, much cleaner. Note that your catch block and finally block executes even if you code as follows: return rows > 0; Or: isSuccess = row > 0; Instead of if (success== true ) Just say: if (success) Much readable and demonstrates that you really understand data types and not a novice in coding. Also would highly recommed that you use stored procedures.

love code · Answer

Usefull feedback. Thanks. At the moment i'm stuck to get the validation, step-2 done properly. What is a effective way the above so i don't re-invent the solution... ?- Sourcecode, please see .zip I'm looking for clear and effectieve way to validate the 'groupbox fields' when they are activated via the Add buttton. Regarding the Add-function, i need to implement the function to; - validate that all fields are the right datatype. - If there is no empty data-input - are smart timesavers, or ways to reuse the soursecode what i'm overlooking ? Let me know. - obligated fill in the whole form, before a new entry is added. Regaring the Update-fuction in my opion i need to; - Validate if, the data-input is valid. Just plain validation. I gone validate on text, @ sign, int. phonenumber 003120434646 with a numberlimit and a . If the result is false; update the changed data-fields. If the result is correct show a error. Suggestions?