Csharp/CSharp Tutorial/ADO.Net/SqlCommand Delete
Delete data using sql statements
<source lang="csharp">using System; using System.Data; using System.Data.SqlClient; class MainClass {
static void Main(string[] args) { SqlConnection MyConnection = new SqlConnection("server=(local)\\SQLEXPRESS;database=MyDatabase;Integrated Security=SSPI;"); MyConnection.Open(); String MyString = "DELETE Employee"; SqlCommand MyCmd = new SqlCommand(MyString, MyConnection); MyCmd.ExecuteScalar(); MyConnection.Close(); }
}</source>
Deleting Data
<source lang="csharp">using System; using System.Data; using System.Data.SqlClient; using System.Collections.Generic; using System.Text;
class Program { static void Main(string[] args) { SqlConnection thisConnection = new SqlConnection( @"Data Source=.\SQLEXPRESS;" + @"AttachDbFilename="NORTHWND.MDF";" + @"Integrated Security=True;Connect Timeout=30;User Instance=true"); SqlDataAdapter thisAdapter = new SqlDataAdapter("SELECT CustomerID, CompanyName FROM Customers", thisConnection); SqlCommandBuilder thisBuilder = new SqlCommandBuilder(thisAdapter); DataSet thisDataSet = new DataSet(); thisAdapter.Fill(thisDataSet, "Customers"); Console.WriteLine("# rows before change: {0}",thisDataSet.Tables["Customers"].Rows.Count); DataColumn[] keys = new DataColumn[1]; keys[0] = thisDataSet.Tables["Customers"].Columns["CustomerID"]; thisDataSet.Tables["Customers"].PrimaryKey = keys; DataRow findRow = thisDataSet.Tables["Customers"].Rows.Find("1"); findRow.Delete(); int rowsAffected = thisAdapter.Update(thisDataSet, "Customers"); Console.WriteLine("Deleted {0} rows.", rowsAffected); Console.WriteLine(thisDataSet.Tables["Customers"].Rows.Count); thisConnection.Close(); } }</source>
Execute nonquery to delete a record (row)
<source lang="csharp">using System; using System.Data; using System.Data.SqlClient; class MainClass {
static void Main() { SqlConnection conn = new SqlConnection("server=(local)\\SQLEXPRESS;database=MyDatabase;Integrated Security=SSPI;"); string sqlqry = @"select count(*) from employee "; string sqlins = @"insert into employee (firstname,lastname)values("Z", "Z")"; string sqldel = @"delete from employee where firstname = "Z" and lastname = "Z""; SqlCommand cmdqry = new SqlCommand(sqlqry, conn); SqlCommand cmdnon = new SqlCommand(sqlins, conn); try { conn.Open(); Console.WriteLine("Before INSERT: Number of employees {0}\n", cmdqry.ExecuteScalar()); Console.WriteLine("Executing statement {0}", cmdnon.rumandText); cmdnon.ExecuteNonQuery(); Console.WriteLine("After INSERT: Number of employees {0}\n", cmdqry.ExecuteScalar()); cmdnon.rumandText = sqldel; Console.WriteLine("Executing statement {0}", cmdnon.rumandText); cmdnon.ExecuteNonQuery(); Console.WriteLine("After DELETE: Number of employees {0}\n", cmdqry.ExecuteScalar()); } catch (SqlException ex) { Console.WriteLine(ex.ToString()); } finally { conn.Close(); Console.WriteLine("Connection Closed."); } }
}</source>