Jeff,
For the best answers try one of FoxPro newsgroup for this, they can as well
tell you what you can use the best to get good performance.
Cor
"Jeff Johnson" <(E-Mail Removed)> schreef in bericht
news:(E-Mail Removed)...
>I am in Interop Hell.
>
> I'm writing a C# program that needs to write to a dBASE III file.
> ADO.NET's performance with ISAMs is abysmal, a fact that I have not only
> read online but have experience firsthand. The recommend solution is to
> use plain old ADO, which is the direction I went. However, I'm getting the
> following error: "Parameter ?_1 has no default value," and it's a nasty
> one. All the hits I found on this error relate to people using ADO.NET,
> not ADO, so hopefully someone can help me. If this is the wrong place to
> ask, please point me in the right direction. Below is the code I am
> currently using, with some redundant stuff stripped out for size reasons:
>
> **************CODE*************
> ConnectionClass cnn = new ConnectionClass();
>
> cnn.Open(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\TEMP;Extended
> Properties=dBASE III;", null, null,
> (int)ConnectOptionEnum.adConnectUnspecified);
>
> object recs;
> // There's earlier code that deletes the DBF if it exists, so this
> statement never fails
> cnn.Execute("CREATE TABLE [TESTIMP] ([PREFIX] VARCHAR(10), [FIRSTNAME]
> VARCHAR(23), [MIDDLENAME] VARCHAR(1), [LASTNAME] VARCHAR(35), [SUFFIX]
> VARCHAR(10), [FULLNAME] VARCHAR(60), <and a bunch of other fields>)", out
> recs, (int)ExecuteOptionEnum.adExecuteNoRecords);
>
> CommandClass cmd = new CommandClass();
> cmd.ActiveConnection = cnn;
> // YEAR must be escaped because apparently it's a reserved word in dBASE.
> Without
> // the escape you get a "Syntax error in INSERT command" error.
> cmd.CommandText = "INSERT INTO TESTIMP (FIRSTNAME, LASTNAME, ADDRESS1,
> CITY, STATE, ZIP, PLUS4, JOBNUMBER,BATCH, PHONE, PHONE2, [YEAR], MAKE,
> MODEL, VIN, MILEAGE, DEALERNAME, DLRNMBR, DISTANCE, SALEDATE, RODATE,
> FCSDLRNMBR, FILENAME) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?,
> ?, ?, ?, ?,?,?, ?, ?)";
> cmd.CommandType = CommandTypeEnum.adCmdText;
> Parameter prm = cmd.CreateParameter("FIRSTNAME", DataTypeEnum.adVarChar,
> ParameterDirectionEnum.adParamInput, 23, string.Empty);
> cmd.Parameters.Append(prm);
> prm = cmd.CreateParameter("LASTNAME", DataTypeEnum.adVarChar,
> ParameterDirectionEnum.adParamInput, 30, string.Empty);
> cmd.Parameters.Append(prm);
> // [...] Several more of the same basic parameters, all using VarChar and
> all being
> // initialized to string.Empty
>
> object dummyParams = null;
>
> // Next I read from an SqlDataReader that I opened right before the code
> above and I start filling the command with values from the reader. (In
> other words, I'm exporting from SQL Server to dBASE.)
> while (reader.Read())
> {
> cmd.Parameters["FIRSTNAME"].Value = (reader.IsDBNull(7) ?
> (object)string.Empty : (object)reader.GetString(7));
> cmd.Parameters["LASTNAME"].Value = (reader.IsDBNull(8) ?
> (object)string.Empty : (object)reader.GetString(8));
> // [...] Again, more the same basic code which sets all the other
> parameters, all using string.Empty if the column is NULL
> //cmd.Execute(out recs, ref dummyParams,
> (int)ExecuteOptionEnum.adExecuteNoRecords);
> cmd.Execute(out recs, ref dummyParams, -1); // ERROR HERE
> }
> **************END CODE*************
>
> As indicated, the error occurs on the Execute method call, whether I call
> the one that's commented out or the other one. If I replace all the
> string.Empty's above with DBNull.Value I get the same error. If I replace
> them with a dummy value, like "#", I get the same error.
>
> I took this exact code and put it in a VB6 program (converting C# to VB,
> of course). The only difference is that I took out the datareader part and
> just set the values of the parameters to a constant value. It worked fine,
> i.e., one record was written to the DBF. To be sure I was comparing apples
> and oranges, I did the same thing in my C# program, i.e., I commented out
> the datareader and just set the values of the parameters directly. I got
> the same $%^&^%*^% error.
>
> Any suggestions? Is there any way to "profile" OLEDB calls? In SQL Server,
> I'd use Profiler to see the exact command that was being passed and
> diagnose problems from there.
>
> Oh, something else: when I was using ADO.NET before this (and experienced
> the insanely awful performance), I got the same error and was able to get
> around it because the OleDbParameter object exposed an IsNullable
> property. I set that to true for all the params and the error went away.
> But ADO doesn't have that property, at least not directly on the Parameter
> object. I thought for a moment that maybe it's something that could be
> added to the Properties collection, but I don't know where to find a list
> of valid properties for parameters. I examined the collection in debug
> mode but it had 0 entries, so that was no help.
>
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