winforms-sql-connection [CALDERON]

TestWins/Form1.cs

@@ -1,13 +1,13 @@
 using System.Drawing.Text;
 using TestWins.Controller;
+using TestWins.Model;
 
 namespace TestWins;
 
 public partial class Form1 : Form
 {
-    //business
-
     private readonly StudentController controller = new StudentController();
+
     public Form1()
     {
         InitializeComponent();
@@ -19,25 +19,105 @@ private void loadData()
         dataGridView1.DataSource = controller.getAll();
     }
 
+    private void ClearFields()
+    {
+        txtStudentId.Clear();
+        txtName.Clear();
+        txtAge.Clear();
+        txtCourse.Clear();
+    }
+
     private void btnAdd_Click(object sender, EventArgs e)
     {
+        try
+        {
+            var student = new Student
+            {
+                studentId = txtStudentId.Text,
+                Name = txtName.Text,
+                age = int.Parse(txtAge.Text),
+                course = txtCourse.Text
+            };
 
+            controller.createStudent(student);
+            MessageBox.Show("Student added successfully!", "Success", MessageBoxButtons.OK, MessageBoxIcon.Information);
+
+            loadData();
+            ClearFields();
+        }
+        catch (Exception ex)
+        {
+            MessageBox.Show($"Error adding student: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
+        }
     }
 
     private void btnUpdate_Click(object sender, EventArgs e)
     {
+        try
+        {
+            if (string.IsNullOrWhiteSpace(txtStudentId.Text))
+            {
+                MessageBox.Show("Please select a student to update.", "Warning", MessageBoxButtons.OK, MessageBoxIcon.Warning);
+                return;
+            }
 
+            var student = new Student
+            {
+                studentId = txtStudentId.Text,
+                Name = txtName.Text,
+                age = int.Parse(txtAge.Text),
+                course = txtCourse.Text
+            };
+
+            controller.update(student);
+            MessageBox.Show("Student updated successfully!", "Success", MessageBoxButtons.OK, MessageBoxIcon.Information);
+
+            loadData();
+            ClearFields();
+        }
+        catch (Exception ex)
+        {
+            MessageBox.Show($"Error updating student: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
+        }
     }
 
     private void btnDelete_Click(object sender, EventArgs e)
     {
+        try
+        {
+            if (string.IsNullOrWhiteSpace(txtStudentId.Text))
+            {
+                MessageBox.Show("Please select a student to delete.", "Warning", MessageBoxButtons.OK, MessageBoxIcon.Warning);
+                return;
+            }
 
-
-
+            var confirmResult = MessageBox.Show("Are you sure to delete this student?", "Confirm Delete", MessageBoxButtons.YesNo, MessageBoxIcon.Question);
+            if (confirmResult == DialogResult.Yes)
+            {
+                controller.delete(txtStudentId.Text);
+                MessageBox.Show("Student deleted successfully!", "Success", MessageBoxButtons.OK, MessageBoxIcon.Information);
+
+                loadData();
+                ClearFields();
+            }
+        }
+        catch (Exception ex)
+        {
+            MessageBox.Show($"Error deleting student: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
+        }
     }
 
     private void dataGridView1_CellClick(object sender, EventArgs e)
     {
-
+        // Ensure the user clicked a valid row (not the headers)
+        if (e.RowIndex >= 0)
+        {
+            DataGridViewRow row = dataGridView1.Rows[e.RowIndex];
+
+            txtStudentId.Text = row.Cells["studentId"].Value?.ToString();
+            txtName.Text = row.Cells["Name"].Value?.ToString();
+            txtAge.Text = row.Cells["age"].Value?.ToString();
+            txtCourse.Text = row.Cells["course"].Value?.ToString();
+        }
     }
 }

TestWins/model/ConnectionSql.cs

@@ -1,22 +1,14 @@
 namespace TestWins.Model;
 
-//dotnet add package MySql.Data
 using MySql.Data.MySqlClient;
 
 public class ConnectionSql
 {
     private readonly string _connectionString = "server=localhost;database=student;uid=root;pwd=root";
-        private MySqlConnection _conn;
 
     public MySqlConnection connectSql()
     {
-
-        Console.WriteLine("Connecting to DB");
-
-        _conn = new MySqlConnection(_connectionString);
-
-        Console.WriteLine(_conn == null ? "Datbase Connection Failed" : "Database connection successful");
-
-        return _conn;
+        // Return a fresh connection object. The 'using' blocks in your repository will handle opening and disposing it.
+        return new MySqlConnection(_connectionString);
     }
-}
+}

TestWins/repository/StudentRepository.cs

@@ -1,25 +1,22 @@
-//Imports
 using MySql.Data.MySqlClient;
 using TestWins.Model;
 
 namespace TestWins.Repoository;
 
-
 public class StudentRepository
 {
-
     private readonly ConnectionSql _db = new ConnectionSql();
 
-    //Create CRUD functionalities
     public void create(Student student)
     {
-        using var conn = _db.connectSql(); //Connection
-        conn.Open(); //Open Connection
-
-        string query = "INSERT INTO students VALUES(@name, @age, @course)";
+        using var conn = _db.connectSql();
+        conn.Open();
 
+        // Explicitly defining columns prevents errors if the DB schema order changes
+        string query = "INSERT INTO students (studentId, name, age, course) VALUES (@id, @name, @age, @course)";
         using var cmd = new MySqlCommand(query, conn);
 
+        cmd.Parameters.AddWithValue("@id", student.studentId);
         cmd.Parameters.AddWithValue("@name", student.Name);
         cmd.Parameters.AddWithValue("@age", student.age);
         cmd.Parameters.AddWithValue("@course", student.course);
@@ -30,7 +27,6 @@ public void create(Student student)
     public List<Student> getAll()
     {
         var list = new List<Student>();
-
         using var conn = _db.connectSql();
         conn.Open();
 
@@ -48,16 +44,15 @@ public List<Student> getAll()
                 course = reader.GetString(3),
             });
         }
-
         return list;
     }
+
     public void update(Student student)
     {
         using var conn = _db.connectSql();
         conn.Open();
 
-        string query = "UPDATE students SET name = @name, age=@age, course=@course where studentId = @ID";
-
+        string query = "UPDATE students SET name = @name, age=@age, course=@course WHERE studentId = @id";
         using var cmd = new MySqlCommand(query, conn);
 
         cmd.Parameters.AddWithValue("@id", student.studentId);
@@ -66,20 +61,18 @@ public void update(Student student)
         cmd.Parameters.AddWithValue("@course", student.course);
 
         cmd.ExecuteNonQuery();
-
     }
 
     public void delete(string id)
     {
         using var conn = _db.connectSql();
-
         conn.Open();
 
         string query = "DELETE FROM students WHERE studentId = @id";
-
         using var cmd = new MySqlCommand(query, conn);
-
+
+        // FIX: The parameter was missing here!
+        cmd.Parameters.AddWithValue("@id", id); 
         cmd.ExecuteNonQuery();
     }
-
-}
+}