C# 错误必须声明标量变量“@EmpID”SQL 插入

Question

我已经坚持这个问题好几个星期了，我已经在各个论坛上尝试解决其他人遇到的相同问题，但到目前为止它仍然行不通。我不确定我做错了什么。

我正在制作一个用户交互页面，该页面在单击按钮保存数据时获取数据并将其提交/插入到 SQL 数据库中。

EmpID 是来自生成用户员工 ID 的文本框的数据。然后将 EmpID 作为 EmployeeID 值存储在 SQL 数据库中。

当我运行它并尝试保存数据时，我一直收到错误；

"Must declare scalar variable "@EmpID

void UpdateInternal0()
{
    try
    {
        using (SqlConnection con = new SqlConnection(Properties.Settings.Default.adminConnectionString))

        {
            con.Open();

            foreach (DataRowView drv in InternalGrid0.SelectedItems)
            {

                DataRow row = drv.Row;
                bool isSelected = Convert.ToBoolean(drv.Row[0]);
                if (isSelected)
                {

                    string sqlString = "INSERT INTO ChecklistTransitionTable (RelatedEmployeeID, RelatedDocIdx) " +
                                       "VALUES (@EmpID, @DOC_Number)";

                    using (SqlCommand cmd = new SqlCommand(sqlString, con))
                    {

                        for (int i = 0; i < InternalGrid0.Columns.Count; i++)
                        {


                            int DocIdx = (int)drv.Row[i];
                            int EmployeeID = Convert.ToInt32(EmpID.Text);


                            cmd.Parameters.AddWithValue("@EmpID", EmployeeID);
                            cmd.Parameters.AddWithValue("@DOC_Number", DocIdx);


                            cmd.ExecuteScalar(); cmd.Parameters.Clear();
                            int result = cmd.ExecuteNonQuery();


                            Console.WriteLine("Test");
                            //Check Error
                            if (result < 0)
                            {

                                System.Windows.Forms.MessageBox.Show("Error inserting data into database!");
                            }
                        }

                    }
                }
            }
        }

        System.Windows.Forms.MessageBox.Show("Employee data successfully updated.");
    }

    catch (SqlException ex)
    {

        System.Windows.Forms.MessageBox.Show(string.Format("\nMessage ---\n{0}", ex.Message));
    }
}

private void BtnGridUpdate_Click(object sender, EventArgs e)
{
    UpdateInternal0();
}

Answer 1

您正在执行查询两次。第一次使用 ExecuteScalar()，然后在 ExecuteNonQuery() 调用中清除参数值并重新执行查询（现在没有参数值）。后者抛出异常

也许这个修改后的版本会按预期工作。

void UpdateInternal0(int employeeId)
{
    try
    {
        using (SqlConnection con = new SqlConnection(Properties.Settings.Default.adminConnectionString))
        {
            con.Open();

            foreach (DataRowView drv in InternalGrid0.SelectedItems)
            {
                DataRow row = drv.Row;
                bool isSelected = Convert.ToBoolean(drv.Row[0]);
                if (isSelected)
                {
                    string sqlString = "INSERT INTO ChecklistTransitionTable (RelatedEmployeeID, RelatedDocIdx) VALUES (@EmpID, @DOC_Number)";

                    using (SqlCommand cmd = new SqlCommand(sqlString, con))
                    {
                        for (int i = 0; i < InternalGrid0.Columns.Count; i++)
                        {
                            int DocIdx = 0;
                            try { 
                                 DocIdx = (int)drv.Row[i];
                            } catch (InvalidCastException ice) {
                                 // You should handle this here...
                            }

                            cmd.Parameters.AddWithValue("@EmpID", employeeId);
                            cmd.Parameters.AddWithValue("@DOC_Number", DocIdx);

                            int result = cmd.ExecuteNonQuery();
                            cmd.Parameters.Clear();

                            Console.WriteLine("Test");
                            //Check Error
                            if (result < 0)
                            {
                                System.Windows.Forms.MessageBox.Show("Error inserting data into database!");
                            }
                        }
                    }
                }
            }
        }
        System.Windows.Forms.MessageBox.Show("Employee data successfully updated.");
    }

    catch (SqlException ex)
    {
        System.Windows.Forms.MessageBox.Show(string.Format("\nMessage ---\n{0}", ex.Message));
    }
}

private void BtnGridUpdate_Click(object sender, EventArgs e)
{
    int employeeID = Convert.ToInt32(EmpID.Text);
    UpdateInternal0(employeeID);
}

C# 错误必须声明标量变量“@EmpID”SQL 插入

C# Error Must declare the scalar variable "@EmpID" SQL Insert

c#

sql

variables

scalar