为什么整数值没有插入到访问数据库中

Question

我正在尝试将整数值插入到访问数据库中，但它给我对象无法从 DBNull 转换为其他类型。错误，但在 datagridview 中我输入了一个值，但仍然显示此错误

string Medicine_Name = dataGridView1.Rows[e.RowIndex].Cells["Medicine_Name"].Value.ToString();
            string Dealer_name = dataGridView1.Rows[e.RowIndex].Cells["Dealer_name"].Value.ToString();
            int Availability =Convert.ToInt16(dataGridView1.Rows[e.RowIndex].Cells["Availability"].Value); 


                if (dataGridView1.IsCurrentRowDirty)
                {
                    string connectionString = null;
                    connectionString = ConfigurationManager.ConnectionStrings["AccessConnectionString"].ConnectionString;
                    con.ConnectionString = connectionString;

                     string cmd1 = "insert into Medicine_Available_Detail(Medicine_Name,Dealer_name,Availability) values(@Medicine_Name,@Dealer_name,@Availability)";
                      OleDbCommand cmd = new OleDbCommand(cmd1, con);

                      cmd.CommandType = CommandType.Text;
                      cmd.Parameters.AddWithValue("@Medicine_Name",Medicine_Name);
                      cmd.Parameters.AddWithValue("@Dealer_name", Dealer_name);
                      cmd.Parameters.AddWithValue("@Availability", Availability);
 con.Open();
                    int n = cmd.ExecuteNonQuery();
                    con.Close();
                    if (n > 0)
                    {

                        MessageBox.Show("Data Inserted Successfully", "Data Inserted ", MessageBoxButtons.OK, MessageBoxIcon.Information);


                    }

                }

Answer 1

"pencil" 表示正在编辑该行，因此 - 即使输入值为 2 - Availability 的值很可能为空。

所以你的概念似乎有问题；当 dataGridView1.IsCurrentRowDirty 为 true 但当它为 false.

时，您不应尝试插入数据

Answer 2

终于找到了解决方案我将我的代码 dataGridView1_RowLeave 更改为 dataGridView1_CellValueChanged 并且它工作正常

private void dataGridView1_CellValueChanged(object sender, DataGridViewCellEventArgs e)
{
med_id = dataGridView1.Rows[e.RowIndex].Cells["Med_id"].Value.ToString();

if (med_id == "")
{
med_id1 = 0;
}
else
{
med_id1 = Convert.ToInt32( dataGridView1.Rows[e.RowIndex].Cells["Med_id"].Value.ToString());

}
if (med_id1 == 0)
{
try
{
string Medicine_Name = dataGridView1.Rows[e.RowIndex].Cells["Medicine_Name"].Value.ToString();
string Dealer_name = dataGridView1.Rows[e.RowIndex].Cells["Dealer_name"].Value.ToString();
int Availability = Convert.ToInt32(dataGridView1.Rows[e.RowIndex].Cells["Availability"].Value.ToString());
string cmd1 = "insert into Medicine_Available_Detail(Medicine_Name,Dealer_name,Availability) values(@Medicine_Name,@Dealer_name,@Availability)";
OleDbCommand cmd = new OleDbCommand(cmd1, con);

cmd.CommandType = CommandType.Text;
cmd.Parameters.AddWithValue("@Medicine_Name", Medicine_Name);
cmd.Parameters.AddWithValue("@Dealer_name", Dealer_name);
cmd.Parameters.AddWithValue("@Availability", Availability);
con.Open();
int n = cmd.ExecuteNonQuery();
con.Close();
if (n > 0)
{

MessageBox.Show("Data Inserted Successfully", "Data Inserted ", MessageBoxButtons.OK, MessageBoxIcon.Information);


}
Load_data();
dataGridView1.Refresh();
}
catch (Exception ex)
{

}


}
else
{
string Medicine_Name = dataGridView1.Rows[e.RowIndex].Cells["Medicine_Name"].Value.ToString();
string Dealer_name = dataGridView1.Rows[e.RowIndex].Cells["Dealer_name"].Value.ToString();
int Availability = Convert.ToInt32(dataGridView1.Rows[e.RowIndex].Cells["Availability"].Value.ToString());
cmd = new OleDbCommand();

cmd.CommandType = CommandType.Text;
cmd = con.CreateCommand();
cmd.CommandText = "update Medicine_Available_Detail set Medicine_Name='" + dataGridView1.Rows[e.RowIndex].Cells["Medicine_Name"].Value.ToString() + "',Dealer_name='" + dataGridView1.Rows[e.RowIndex].Cells["Dealer_name"].Value.ToString() + "',Availability='" + Convert.ToInt32(dataGridView1.Rows[e.RowIndex].Cells["Availability"].Value.ToString())+ "'where Med_id=" + med_id1 + "";
con.Open();
int n = cmd.ExecuteNonQuery();
con.Close();
if (n > 0)
{

MessageBox.Show("Data Updated Successfully", "Data Inserted ", MessageBoxButtons.OK, MessageBoxIcon.Information);


}
Load_data();
dataGridView1.Refresh();

}
}

为什么整数值没有插入到访问数据库中

why Integer value is not inserted in access database

c#

datagridview

ms-access-2007