C# 标准表达式中的数据类型不匹配

Question

The following code raises an exception datatype mistmach in criteria expression . Where does the exception come from? Generated query works in Microsoft Access with no problems.

foreach (DataColumn column in dt.Columns)
{
    if (column.DataType == typeof(String))
    {
        if (column.ColumnName != "ID1" && column.ColumnName != "ID" && column.ColumnName != "Geometry" && column.ColumnName != "Geometry_SK")
        {
            string query = "UPDATE " + tb_tablename.Text.Trim() + " SET " + column.ColumnName + " = Replace([" + column.ColumnName + "], Chr(10), \"\");";

            using (OleDbCommand cmd = new OleDbCommand(query, conn))
            {
                cmd.ExecuteNonQuery();
            }
        }
    }
}

As example generated SQL code is UPDATE Necropolis SET NAME_MR = Replace([NAME_MR], Chr(10), ""); . After generating its execute with cmd.ExecuteNonQuery();

Parameters version shows Syntax error in query. Incomplete query clause. Syntax error in query. Incomplete query clause. .

using (OleDbCommand cmd = new OleDbCommand(query, conn))
                            {
                                cmd.CommandType = CommandType.Text;
                                cmd.CommandText = "UPDATE @target SET [@columnname] = Replace([@columnname], Chr(10), '');";

                                cmd.Parameters.Add(new OleDbParameter("@target", OleDbType.VarChar)).Value = tb_tablename.Text.Trim();
                                cmd.Parameters.Add(new OleDbParameter("@columnname", OleDbType.VarChar)).Value = column.ColumnName;

                                MessageBox.Show(cmd.CommandText);

                                cmd.ExecuteNonQuery();
                            }

Answer 1

are you sure, that query gives a valid SQL statement? I am not sure, but =Replace([xyz], Chr(10), \"\"); does not look like a valid SQL statement fo me... I think, you should use two seperate strings for the columname:

string col_org = column.ColumnName;
string col_new = column.ColumnName.Replace(Chr(10), "\"");
string query = "UPDATE " + tb_tablename.Text.Trim() + " SET " + col_org + " = " + "+ col_new + ";";

Can you give us an example of the update string?