Question

请查找附件，我编写的代码，但是当它运行时以及当我以表格形式输入数据时n点击提交它会在"Command.executenonquery statement"给我错误。

显示Invalid Operation exception was mishandled

namespace WindowsFormsApplication2
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void button1_Click(object sender, EventArgs e)
        {
            if (radioButton1.Checked == true)
            {
                OleDbConnection conn = new OleDbConnection();
                conn.ConnectionString = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\databses\electric_data.accdb";
                OleDbCommand command = new OleDbCommand();
                command.CommandText = "INSERT INTO Electric_Data (Asset_Id,Asset_Name,Emp_Id,Type_of_Asset,Actual_Start_date) VALUES (?,?,?,?,?)";
                command.Parameters.Add("@Asset_Id", OleDbType.VarChar, 20).Value = textBox1.Text;
                command.Parameters.Add("@Asset_Name", OleDbType.Char, 20).Value = textBox2.Text;
                command.Parameters.Add("@Type_of_Asset", OleDbType.VarChar, 20).Value = textBox3.Text;
                command.Parameters.Add("@Emp_Id", OleDbType.Char, 20).Value = textBox4.Text;
                command.Parameters.Add("@Actual_Start_date", OleDbType.Date).Value = DateTime.Now;
                command.ExecuteNonQuery();
                conn.Open();
                command.Connection = conn;

                MessageBox.Show("Entry Registered Successfully.");
            }
            if (radioButton2.Checked == true)
            {
                OleDbConnection conn = new OleDbConnection();
                conn.ConnectionString = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\databses\electric_data.accdb";
                OleDbCommand command = new OleDbCommand();
                command.CommandText = "INSERT INTO Electric_Data (Asset_Id,Asset_Name,Emp_Id,Type_of_Asset,Actual_end_date) VALUES (?,?,?,?,?)";
                command.Parameters.Add("@Asset_Id", OleDbType.VarChar, 20).Value = textBox1.Text;
                command.Parameters.Add("@Asset_Name", OleDbType.Char, 20).Value = textBox2.Text;
                command.Parameters.Add("@Emp_Id", OleDbType.VarChar, 20).Value = textBox3.Text;
                command.Parameters.Add("@Type_of_Asset", OleDbType.VarChar, 20).Value = textBox4.Text;
                command.Parameters.Add("@Actual_end_date", OleDbType.Date).Value = DateTime.Now;
                command.ExecuteNonQuery();
                conn.Open();
                command.Connection = conn;

                MessageBox.Show("Entry Registered Successfully.");
            }

            else if (radioButton1.Checked == false && radioButton2.Checked == false)
                MessageBox.Show("Check Work_Start or Work_Complete option for successful Entry.");
        }


    }
}

Answer 1

你已经把conn.Open（）放错了地方。试试 - ＆gt;

OleDbConnection conn = new OleDbConnection();
conn.ConnectionString = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\databses\electric_data.accdb";
OleDbCommand command = new OleDbCommand();
command.CommandText = "INSERT INTO Electric_Data (Asset_Id,Asset_Name,Emp_Id,Type_of_Asset,Actual_Start_date) VALUES (@Asset_Id,@Asset_Name,@Emp_Id,@Type_of_Asset,@Actual_end_date)";   
command.Parameters.Add("@Asset_Id", OleDbType.VarChar, 20).Value = textBox1.Text;
command.Parameters.Add("@Asset_Name", OleDbType.Char, 20).Value = textBox2.Text;
command.Parameters.Add("@Emp_Id", OleDbType.VarChar, 20).Value = textBox3.Text;
command.Parameters.Add("@Type_of_Asset", OleDbType.VarChar, 20).Value = textBox4.Text;
command.Parameters.Add("@Actual_end_date", OleDbType.Date).Value = DateTime.Now;

// Open connection and assign to command
conn.Open();
command.Connection = conn;

// Execute non-query command
command.ExecuteNonQuery();

暂且不说：

您不需要在代码中复制conn字符串，列名等。做一个噩梦来维护和调试。
您需要添加try ... catch异常处理 - 如果DB由于某种原因没有打开怎么办。

编辑：command.CommandText也是其他学识渊博的人的错误。

Answer 2

您的命令文本完全错误。使用您的参数名称更改问号：

 command.CommandText = "INSERT INTO Electric_Data (Asset_Id,Asset_Name,Emp_Id,Type_of_Asset,Actual_Start_date) VALUES (@Asset_Id,@Asset_Name,@Emp_Id,@Type_of_Asset,@Actual_end_date)";

您在ExecuteNonQuery之后打开连接，首先打开连接，然后执行查询

conn.Open();
command.Connection = conn;    
command.ExecuteNonQuery();

Answer 3

尝试此插入查询。移除?,?,?,?

 command.CommandText = "INSERT INTO Electric_Data (Asset_Id,Asset_Name,Emp_Id,Type_of_Asset,Actual_Start_date) VALUES (@Asset_Id,@Asset_Name,@Emp_Id,@Type_of_Asset,@Actual_end_date)";

检查表格列的数据类型

我正在尝试根据选择在Access DB中插入数据

3 个答案: