sql - Delete selected rows in datagridview from database

Sql - Delete selected rows in datagridview from database

Deleting selected rows in a DataGridView and subsequently from a database can be achieved through several steps. Here's a detailed guide to help you perform this operation using C# with a Windows Forms application connected to a database (e.g., SQL Server).

Steps to Delete Selected Rows

  1. Setup Your DataGridView: Ensure your DataGridView is populated with data from your database. This usually involves setting up a data binding between the DataGridView and a DataSet or DataTable.

  2. Handle Row Selection: Implement logic to determine which rows are selected for deletion.

  3. Delete Selected Rows from Database: Execute SQL DELETE statements to remove the corresponding records from the database.

  4. Update DataGridView: Remove the deleted rows from the DataGridView to reflect the changes.

Example Implementation

Here is a step-by-step example in C#:

1. Populate DataGridView

First, populate the DataGridView with data from the database:

private void LoadData() { using (SqlConnection conn = new SqlConnection("your_connection_string")) { string query = "SELECT * FROM your_table"; SqlDataAdapter adapter = new SqlDataAdapter(query, conn); DataTable dt = new DataTable(); adapter.Fill(dt); dataGridView1.DataSource = dt; } }

2. Add a Button for Deletion

Add a button to your form that will trigger the deletion process:

private void deleteButton_Click(object sender, EventArgs e) { DeleteSelectedRows(); }

3. Delete Selected Rows

Implement the DeleteSelectedRows method to delete the selected rows:

private void DeleteSelectedRows() { // Assuming the first column is the primary key string primaryKeyColumn = "id"; // Adjust according to your table's primary key // Create a list to hold the IDs of the rows to be deleted List<int> idsToDelete = new List<int>(); foreach (DataGridViewRow row in dataGridView1.SelectedRows) { if (row.Cells[primaryKeyColumn].Value != null) { int id = Convert.ToInt32(row.Cells[primaryKeyColumn].Value); idsToDelete.Add(id); } } // Delete rows from the database using (SqlConnection conn = new SqlConnection("your_connection_string")) { conn.Open(); foreach (int id in idsToDelete) { string deleteQuery = "DELETE FROM your_table WHERE id = @id"; using (SqlCommand cmd = new SqlCommand(deleteQuery, conn)) { cmd.Parameters.AddWithValue("@id", id); cmd.ExecuteNonQuery(); } } } // Remove rows from the DataGridView foreach (DataGridViewRow row in dataGridView1.SelectedRows) { dataGridView1.Rows.Remove(row); } }

Full Example in Context

Here's how you can put it all together in a simple form with a DataGridView and a Delete button:

using System; using System.Collections.Generic; using System.Data; using System.Data.SqlClient; using System.Windows.Forms; public partial class MainForm : Form { public MainForm() { InitializeComponent(); LoadData(); } private void LoadData() { using (SqlConnection conn = new SqlConnection("your_connection_string")) { string query = "SELECT * FROM your_table"; SqlDataAdapter adapter = new SqlDataAdapter(query, conn); DataTable dt = new DataTable(); adapter.Fill(dt); dataGridView1.DataSource = dt; } } private void deleteButton_Click(object sender, EventArgs e) { DeleteSelectedRows(); } private void DeleteSelectedRows() { string primaryKeyColumn = "id"; // Adjust according to your table's primary key List<int> idsToDelete = new List<int>(); foreach (DataGridViewRow row in dataGridView1.SelectedRows) { if (row.Cells[primaryKeyColumn].Value != null) { int id = Convert.ToInt32(row.Cells[primaryKeyColumn].Value); idsToDelete.Add(id); } } using (SqlConnection conn = new SqlConnection("your_connection_string")) { conn.Open(); foreach (int id in idsToDelete) { string deleteQuery = "DELETE FROM your_table WHERE id = @id"; using (SqlCommand cmd = new SqlCommand(deleteQuery, conn)) { cmd.Parameters.AddWithValue("@id", id); cmd.ExecuteNonQuery(); } } } foreach (DataGridViewRow row in dataGridView1.SelectedRows) { dataGridView1.Rows.Remove(row); } } }

Notes

  • Ensure proper exception handling and validation.
  • Adjust the connection string and table/column names to match your database schema.
  • This example assumes the id column is the primary key. Modify it according to your actual schema.
  • If your DataGridView is bound to a DataSource, you may need to refresh the data source after deletion instead of manually removing rows.

Examples

  1. SQL query to delete selected rows in DataGridView from database using primary key:

    • Description: This query deletes selected rows from the database based on their primary key values retrieved from the DataGridView.
    DELETE FROM table_name WHERE primary_key_column IN (selected_primary_key_values);

  2. SQL query to delete selected rows in DataGridView from database using a unique identifier:

    • Description: This query deletes selected rows from the database based on a unique identifier column retrieved from the DataGridView.
    DELETE FROM table_name WHERE unique_identifier_column IN (selected_unique_identifiers);

  3. SQL query to delete selected rows in DataGridView from database using WHERE clause:

    • Description: This query deletes selected rows from the database by specifying conditions in the WHERE clause based on selected values from the DataGridView.
    DELETE FROM table_name WHERE condition_column = selected_value;

  4. SQL query to delete selected rows in DataGridView from database using batch processing:

    • Description: This query deletes selected rows from the database in a batch using a single DELETE statement for improved performance.
    DELETE FROM table_name WHERE primary_key_column IN (selected_primary_key_values);

  5. SQL query to delete selected rows in DataGridView from database with user-defined function:

    • Description: This query invokes a user-defined function to delete selected rows from the database, allowing for customized delete logic.
    DELETE FROM table_name WHERE primary_key_column = dbo.DeleteSelectedRowsFunction(selected_value);

  6. SQL query to delete selected rows in DataGridView from database with stored procedure:

    • Description: This query calls a stored procedure to delete selected rows from the database, encapsulating the delete logic within the procedure.
    EXEC DeleteSelectedRowsProcedure @selected_value;

  7. SQL query to delete selected rows in DataGridView from database using temporary table:

    • Description: This query deletes selected rows from the database by first populating a temporary table with selected values from the DataGridView.
    DELETE FROM table_name WHERE primary_key_column IN (SELECT selected_primary_key_values FROM #temp_table);

  8. SQL query to delete selected rows in DataGridView from database using subquery:

    • Description: This query deletes selected rows from the database by using a subquery to filter rows based on selected values from the DataGridView.
    DELETE FROM table_name WHERE primary_key_column IN (SELECT selected_primary_key_values FROM table_name WHERE condition_column = selected_value);

  9. SQL query to delete selected rows in DataGridView from database with transaction handling:

    • Description: This query deletes selected rows from the database within a transaction to ensure data integrity and rollback in case of errors.
    BEGIN TRANSACTION; DELETE FROM table_name WHERE primary_key_column IN (selected_primary_key_values); COMMIT;

  10. SQL query to delete selected rows in DataGridView from database using ORM (Object-Relational Mapping):

    • Description: This query utilizes an ORM framework's methods or functions to delete selected rows from the database, simplifying the delete operation.
    // Example using Entity Framework in C#: foreach (var item in selectedItems) { dbContext.Table.Remove(item); } dbContext.SaveChanges();

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