Question

当数据库中存在的序列号输入到文本框中时，会使用消息框成功删除它。问题是，即使文本框为空，它仍然表示它是成功的。

try
    {
         connection.Open();

         OleDbCommand command = new OleDbCommand();
         command.Connection = connection;
         string deleteEntry = "delete from Inventory where SerialNumber='" + txtSerial.Text + "' ";           
         MessageBox.Show(deleteEntry);
         command.CommandText = deleteEntry;
         //TO READ DATA
         command.ExecuteNonQuery();
         MessageBox.Show("Data Has Been Deleted");
         connection.Close(); // CLOSE HERE OR YOU CANNOT EDIT RECORDS SIMULTANEOUSLY
    }
         catch (OleDbException ex)
    {
         MessageBox.Show(ex.Message);
         connection.Close();
    }
    }

Answer 1

如果您希望在txtSerial.Text为空或为空时执行命令，请检查它：

if (!string.IsNullOrEmpty(txtSerial.Text)) {
    try
        {
            connection.Open();
    (...)
} else {
    MessageBox.Show("Error: Provide a Serial")
}

此外，请查看parameterized queries，并考虑在finally块中关闭您的连接，或使用using语句进行连接。

Answer 2

if (txtSerial.Text.Length != 0 ) 
{
    try
    {
        connection.Open();
    } 
    Catch() ....... 
}
else
{     
      MessageBox.Show("Serial Number must be required...");
}

试试这个......

文本为空时防止删除

2 个答案: