Access Database error:: “No value given for one or more required parameters.”

问题

I have a datagridview. In this DGV first colum is a combobox column. I want to make, when this combobox value is selected next fild will be filled automatically from database. But there shows a error.

No value given for one or more required parameters on OleDbDataReader dr1 = cmd1.ExecuteReader();

I post the code. Please help me.

OleDbConnection con = new OleDbConnection(conn);
con.Open();

for (int i = 0; i < dgv.Rows.Count; i++)
{

    string query = "select Description from General where AccCode='" +
        dgv.Rows[i].Cells[0].Value +
        "' and conpanyID='" +
        label1.Text + "'";
    OleDbCommand cmd1 = new OleDbCommand(query, con);
    //OleDbDataAdapter daBranchName = new OleDbDataAdapter(cmd);
    OleDbDataReader dr1 = cmd1.ExecuteReader();
    while (dr1.Read())
    {
        dgv.Rows[i].Cells[1].Value = dr1["Description"].ToString();
    }
}
con.Close();

回答1:

This kind of string concatenations are open for SQL Injection attacks.

Use parameterized queries instead.

string query = "select [Description] from [General] where AccCode= ? and conpanyID= ?";
OleDbCommand cmd1 = new OleDbCommand(query, con);
cmd1.Parameters.AddWithValue("@acc", dgv.Rows[i].Cells[0].Value);
cmd1.Parameters.AddWithValue("@ID", label1.Text);

As HansUp pointed, Description and General are reserved keywords. Use them with square brackets like [Description] and [General]

回答2:

As suggested, use parameterized queries.

As far as the error is concerned, I'm guessing this field name is wrong:

conpanyID=

should be:

companyID=

回答3:

Use Parameters, otherwise it will open for sql injection attacks.

string query = "select [Description] from General where AccCode=? and conpanyID=?";

now you can set parameters

cmd.Parameters.AddWithValue("@p1", val1);
cmd.Parameters.AddWithValue("@p2", val2);

来源：https://stackoverflow.com/questions/18720764/access-database-error-no-value-given-for-one-or-more-required-parameters

标签

winforms

ms-access

datagridview

oledbdatareader