sqlcommand執行查詢不更新刪除並插入

Question

你好，我總是使用SQlcommand非查詢，但現在錯了我不知道我有什麼3按鈕操作更新插入和刪除，但我創建了所有3個操作的唯一方法，問題是它不插入刪除或更新：

private void operacao(String operacao) { 
     String comando = ""; 
     con = new SqlConnection(); 
     WorksDataSet dataset = new WorksDataSet(); 
     con.ConnectionString = @"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Works.mdf;Integrated Security=True;User Instance=True;Asynchronous Processing=true"; 
     try 
     { 
      con.Open(); 

     } 
     catch (SqlException cox) { 
      MessageBox.Show(cox.Message, this.Text, MessageBoxButtons.OK, MessageBoxIcon.Error); 
     } 
     switch (operacao) { 
      case "inserir": 

       try 
       { 
        comando = "Insert Into Estudante (Codigo,Nome,Apelido) values(" + txtID.Text + ",'" + txtNome.Text + "','" + txtapelido.Text + "')"; 
        SqlCommand command = new SqlCommand(comando, con); 
        SqlDataAdapter sda=new SqlDataAdapter(command); 
        command.CommandType = CommandType.Text; 
        sda.Fill(dataset); 
        command.ExecuteNonQuery(); 
        command.Dispose(); 
        MessageBox.Show("Adicionado com Sucesso", this.Text, MessageBoxButtons.OK, MessageBoxIcon.Information); 
       } 
       catch (SqlException sex) { 
        MessageBox.Show(sex.Message , this.Text,MessageBoxButtons.OK,MessageBoxIcon.Error); 
       } 

       break; 

      case "apagar": 
       comando = "delete from Estudante where Codigo=" + txtID; 
       try 
       { 

        SqlCommand command = new SqlCommand(comando, con); 
        command.BeginExecuteNonQuery(); 
        MessageBox.Show("Removido com Sucesso", this.Text, MessageBoxButtons.OK, MessageBoxIcon.Information); 
       } 
       catch (SqlException sex) 
       { 
        MessageBox.Show(sex.Message, this.Text, MessageBoxButtons.OK, MessageBoxIcon.Error); 
       } 
       break; 
      case "atualizar": 
       comando = "update table Estudante set nome='" + txtNome + "'^ apelido='" + txtapelido + "'"; 
       try 
       { 

        SqlCommand command = new SqlCommand(comando, con); 
        command.BeginExecuteNonQuery(); 
        MessageBox.Show("Actualizado com Sucesso", this.Text, MessageBoxButtons.OK, MessageBoxIcon.Information); 
       } 
       catch (SqlException sex) 
       { 
        MessageBox.Show(sex.Message, this.Text, MessageBoxButtons.OK, MessageBoxIcon.Error); 
       } 
       break; 
      default: 
       break 
       ; 
     } 
     con.Close(); 
    } 

Answer 1

您應該使用參數化查詢。總是.....

這對於插入操作。

comando = "Insert Into Estudante (Codigo,Nome,Apelido) values(@id, @nome, @apelido"); 
SqlCommand command = new SqlCommand(comando, con);      
command.Parameters.AddWithValue("@id", txtID.Text); 
command.Parameters.AddWithValue("@nome", txtNome.Text); 
command.Parameters.AddWithValue("@apelido", txtapelido.Text); 
command.CommandType = CommandType.Text;      
command.ExecuteNonQuery(); 

這裏不需要使用數據集或數據適配器。只是ExecuteNonQuery

這是刪除操作。

comando = "delete from Estudante where Codigo=@id"; 
SqlCommand command = new SqlCommand(comando, con); 
command.Parameters.AddWithValue("@id", txtID.Text); 
command.CommandType = CommandType.Text; 
command.ExecuteNonQuery();      

請注意，您應該通過Text屬性，而不是整個文本框

本作的更新運算

comando = "update table Estudante set nome=@nome, apelido=@apelido where codigo=@id"; 
SqlCommand command = new SqlCommand(comando, con); 
command.Parameters.AddWithValue("@id", txtID.Text); 
command.Parameters.AddWithValue("@nome", txtNome.Text); 
command.Parameters.AddWithValue("@apelido", txtapelido.Text); 
command.CommandType = CommandType.Text; 
command.ExecuteNonQuery();      

同樣，此處使用Text屬性不是文本框對象

通過這種方式，您不必擔心字符串參數中的引號，並且您關閉了
的大門

Answer 2

要執行insert/delete/update聲明，您只需創建SqlCommand和SqlConnection對象。 DataSet和DataAdapter沒用。

插入一行：

string cnstr=@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Works.mdf;Integrated Security=True;User Instance=True;Asynchronous Processing=true"; 

using(SqlConnection con = new SqlConnection(cnstr)) 
{ 
    string sql = "Insert Into Estudante (Codigo,Nome,Apelido) values(@Codigo,@Nome,@Apelido)"; 
    using(SqlCommand command= new SqlCommand(sql,con)) 
    { 
    command.Parameters.Add("@Codigo",SqlDbType.Int).Value=txtID.Text; 
    command.Parameters.Add("@Nome",SqlDbType.VarChar,30).Value=txtNome.Text; 
    command.Parameters.Add("@Apelido",SqlDbType.VarChar,30).Value=txtapelido.Text; 
    con.Open(); 
    cmd.ExecuteNonQuery(); 
    con.Close(); 
    } 
} 

Answer 3

您呼叫的的sqlDataAtapter的填充方法來填充這是不必要的數據庫。刪除該語句並查看。這應該工作。