抛出异常：System.Data.dll 中的“System.Data.SqlClient.SqlException”附加信息：将数据类型 varchar 转换为 bigint 时出错。 在 C#

Question

This Is My Codding i have face this type of error in my code

(Exception thrown: 'System.Data.SqlClient.SqlException' in System.Data.dll

Additional information: Error converting data type varchar to bigint

Update Query:___________________________________

private void btnUpdate_Click(object sender, EventArgs e)
{
    query = ("update items set name='" + txtName.Text + "',category='" + txtCategory.Text + "',price='" + txtPrice.Text + "where iid =" + id + "'");
    fn.setData(query);
    loadData();
    txtName.Clear();
    txtCategory.Clear();
    txtPrice.Clear();
}

---

Set Query_______________

public void setData(String query)
{
    SqlConnection con = getConnection();
    SqlCommand cmd = new SqlCommand();
    cmd.Connection = con;
    con.Open();
    cmd.CommandText = query;
    cmd.ExecuteNonQuery();
    con.Close();


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

}

Answer 1

Always try to use Parameterized Query or Stored Procedure , rather than injecting values.

btnUpdate_Click

private void btnUpdate_Click(object sender, EventArgs e)
{
    query = ("update items set name = @name, category = @category, price = @price where iid = @id");
    fn.setData(query,long.Parse(id),txtName.Text, txtCategory.Text, long.Parse(txtPrice.Text));
    loadData();
    txtName.Clear();
    txtCategory.Clear();
    txtPrice.Clear();
}

setData function

public void setData(String query, long id,string name, string category, long price)
{
    SqlConnection con = getConnection();
    SqlCommand cmd = new SqlCommand();
    cmd.Connection = con;
    cmd.CommandText = query;
    cmd.Parameters.AddWithValue("@name", name);
    cmd.Parameters.AddWithValue("@category", category);
    cmd.Parameters.AddWithValue("@price", price);
    cmd.Parameters.Add(new SqlParameter()
    {
        DbType = System.Data.DbType.Int64, //For big int
        Direction = System.Data.ParameterDirection.Input,
        ParameterName = "@id",
        Value = id
    });
    try
    {
        con.Open();
        cmd.ExecuteNonQuery();
        con.Close();
        MessageBox.Show("Data Processed Successfully.", "Success",MessageBoxButtons.OK, MessageBoxIcon.Information);
    }
    catch(Exception ex)
    {
        // catch exception here
    }
}

Answer 2

Change your code as highlighted below, it should solve your problem.

{

query = ("update items set name='" + txtName.Text + "',category='" + txtCategory.Text + "',price= " +int.Parse(txtPrice.Text) + "where iid =" + id + "'");

    fn.setData(query);
    loadData();
    txtName.Clear();
    txtCategory.Clear();
    txtPrice.Clear();
}