Similar to the question answered here https://stackoverflow.com/a/42932812/1321510 we need to execute a raw sql query. For the query we don't have any db context model (so any .FromSql answers won't work for us). However we need to execute it within an existing transaction (created with context.Database.BeginTransaction()). All solutions found on SO do not work with existing transactions.
Example:
var connection = context.Database.GetDbConnection();
using (var command = connection.CreateCommand())
{
command.CommandText = sql;
command.Transaction = context.Database.CurrentTransaction.GetDbTransaction();
var executeReader = command.ExecuteReader();
var values = new object[executeReader.FieldCount];
if (!executeReader.Read())
{
return values;
}
executeReader.GetValues(values);
return values;
}
}
Commiting the transaction then throws System.InvalidOperationException: 'This MySqlConnection is already in use. See https://fl.vu/mysql-conn-reuse'.
The provided link in the exception doesn't seem helpful at all, since we're neither using async nor using the connection whilst reading from it.
We're using Pomelo.EntityFrameworkCore.MySql as the database connector.
i have the following code which has been getting me data from flat files. but now all of a sudden i am getting this error
System.Data.OleDb.OleDbException: Invalid path or file name
but the code hasnt changed it worked for months,im not sure what went wrong.
System.Web.Script.Serialization.JavaScriptSerializer json = new System.Web.Script.Serialization.JavaScriptSerializer();
string jsonText;
System.Collections.Generic.List<object> objList = new List<object>();
string strConn = #"Provider=vfpoledb;Data Source=\\10.0.0.0\wwwroot\apps\assembly\FlatDatabaseDbfs\vt_Flat.dbf;Collating Sequence=machine;";
using (System.Data.OleDb.OleDbConnection conn = new System.Data.OleDb.OleDbConnection(strConn))
{
System.Data.OleDb.OleDbCommand cmddbf = new System.Data.OleDb.OleDbCommand();
cmddbf.Connection = conn;
conn.Open();
cmddbf.CommandText = "select * from vt_Flat";
var dr = cmddbf.ExecuteReader();
while (dr.Read())
{
objList.Add(new
{
Code = (dr["dp_code"].ToString().Trim()),
});
};
}
var filteredList = objList.Where(obj => ((dynamic)obj).Status == (Request.QueryString["Status"] ?? "") && ((dynamic)obj).DepCode == (Request.QueryString["Code"] ?? ""));
jsonText = json.Serialize(filteredList);
Response.Write(jsonText);
}
is there something wrong with iis permissions?
Aside from the connection having to point to the PATH as already noted by Oleg, in the C# instances of OleDbConnection I have done in the past, the connection string uses
Provider=VFPOLEDB.1
Don't know if it is case/sensitive issue and the ".1" which is also part of the provider string.
Once you have a valid connection to the PATH, then your query can query from any table within the path location. So if you had 2+ files, and needed to join them, you would do so with a standard query / join. In your case, your command text is only "select *" since you changed your original connection that included the table. Change the command text to
"select * from vt_Flat"
OTHER CONSIDERATIONS
Is this being run from some web service project? If so, THAT could be the basis. You as a developer testing are running with your permissions / access. If running as a web server, the WEB-based user account may not have permissions to the folder to process / work with the data.
Check the folder of your production data to ALLOW the web user if so running. If that doesn't work, set permissions on the folder to EVERYBODY (only for testing/confirmation purposes only). See if that is the problem.
Also, from the Provider connection, did you try with it as all upper case VFPOLEDB.1?
Use path instead of file name, e.g.:
Data Source=\\10.0.0.0\wwwroot\apps\assembly\FlatDatabaseDbfs\;
I'm having trouble with the implementation of SqlDependency in my project.
I'm using SqlDependency in a WCF Service. WCF Service then holds in memory cache all results from all tables in order to have a huge speed gain. Everything seems to be working fine, except when I'm doing a table row update. If I add or delete a row in my table, DataContext is refreshed and cache is invalidated without problems. But when it comes to a table row update, nothing happens, the cache is not invalidated and when I look in debug mode at the content of DataContext, no changes seems to be there.
Here's the code I'm using (note that I'm using the System.Runtime.Caching object) :
public static List<T> LinqCache<T>(this Table<T> query) where T : class
{
ObjectCache cache = MemoryCache.Default;
string tableName =
query.Context.Mapping.GetTable(typeof(T)).TableName;
List<T> result = cache[tableName] as List<T>;
if (result == null)
{
using (SqlConnection conn =
new SqlConnection(query.Context.Connection.ConnectionString))
{
conn.Open();
SqlCommand cmd = new SqlCommand(
query.Context.GetCommand(query).CommandText, conn);
cmd.Notification = null;
cmd.NotificationAutoEnlist = true;
SqlDependency dependency = new SqlDependency(cmd);
SqlChangeMonitor sqlMonitor =
new SqlChangeMonitor(dependency);
CacheItemPolicy policy = new CacheItemPolicy();
policy.ChangeMonitors.Add(sqlMonitor);
cmd.ExecuteNonQuery();
result = query.ToList();
cache.Set(tableName, result, policy);
}
}
return result;
}
I created an extension method so all I have to do is to query any table like that :
List<MyTable> list = context.MyTable.LinqCache();
My DataContext is opened at the Global.asax Application_OnStart and stored in cache, so I can use it whenever I want in my WCF Service. As well at this moment I'm opening the SqlDependency object with
SqlDependency.Start(
ConfigurationManager.ConnectionStrings[myConnectionString].ConnectionString);
So, is that a limitation of SqlDependency, or I'm doing something wrong/missing something in the process?
I think the problem is that although you do all the work in setting up the command object you then do:
cmd.ExecuteNonQuery();
result = query.ToList();
Which is going to use your SQL Command and throw away the results then LINQ to SQL will generate it's own internally via query.ToList(). Thankfully you can ask LINQ to SQL to execute your own command and translate the results for you so try replacing those two lines with:
results = db.Translate<T>(cmd.ExecuteReader());
How will we use Connection Manager in Script component, using OLEDB Provider ? I had tried using Connection Manager with OLEDB Provider and SQL, but failed. what is the correct way to use ?
The syntax is different between a Script Task and a Script Component. Check out this article for more than a couple side-by-side comparisons:
http://msdn.microsoft.com/en-us/library/ms136031.aspx
This is well documented on MSDN, covering both VB and C# type of scripts: http://msdn.microsoft.com/en-us/library/ms136018.aspx
IDTSConnectionManager100 connMgr = this.Connections.ADONetAppStaging ; //this we need to give name in connection manager in script component
SqlConnection myADONETConnection = new SqlConnection();
myADONETConnection = (SqlConnection)(connMgr.AcquireConnection(null));
//Read data from table or view to data table
string query = "Select top 10 * From ##AP_Stagging_Temp_ExportWODuplicates Order by 1,2,3 asc ";
// string query = "Select * From ##AP_Stagging_Temp_For_JLL_ExportWODuplicates order by 1,2,3 asc ";
SqlDataAdapter adapter = new SqlDataAdapter(query, myADONETConnection);
DataTable dtExcelData = new DataTable();
adapter.Fill(dtExcelData);
myADONETConnection.Close();
I need to export data from a SQL server 2005 DB to an Access 97 .mdb file. The client that needs it, needs it to be Access 97 because the system that they're importing it into requires Access 97 file format (don't get me started). Any suggestions how to write an old-timey Access file from SQL or .Net (or VB6 or Ruby or Python..)?
Thanks in advance,
Lee
I'd let Sql 2005 do it for you.
In the Sql Management Stuidio, right-click on your source database, then Tasks, then Export Data. You can use this to export directly into your Access database, just follow the prompts. Or you can output it to a file format you can use to put into Access.
What you need to do is export into an Access file for whatever Access version you have installed (as long as it's 2000...2003; Access 2007 can't write to Access 97 files). I assume you already know how to do this.
Then you can create an Access object via COM and ask it to convert your new .mdb file into a new Access 97 database. In VBScript, the code looks like this (adjust as necessary if you're using VBA, VB.Net, or another language):
const acFileFormatAccess97 = 8
dim app
set app = CreateObject("Access.Application")
app.ConvertAccessProject "y:\mydatabase.mdb", "y:\mydatabase97.mdb", acFileFormatAccess97
If you have Access 97 installed, the above command won't work, because Access didn't have the ConvertAccessProject function in that version. Of course, you don't need to convert the file in that case anyway.
This might give you a starting point.
And this article is a bit old, but you might be able to pick up something. I can only find those using Jet 4.0 which is compatible w/ Access 2000 as in the previous article. Using the MS Access driver might give you what you want.
After you created the database, use regular ODBC / OLE DB related stuffs in ADO.NET to create your table and populate them w/ your data.
This is a great question! I've actually wanted to be able to do this kind of thing in a programmatic way, but in the past I've had nothing but trouble coming up with it. However, have matured a bit in my .NET skills over the years, I thought I would take a shot at writing a solution that could be executed as a Console app. This can be implemented either as a scheduled task on the windows server or sql server (using the Sql Server agent). I don't see why this couldn't be automated from the Sql Server without the following code, but I really had fun with this, so I just have to put it out there. The table in both Sql and Access is a list of dogs, with an ID, a name, a breed, and a color. Generic stuff. This actually works on my desktop between a local instance of Sql Server and Access (2007, but I don't know why it wouldn't work with 97). Please feel free to critique.
BTW, has the following:
using System.Data;
using System.Data.OleDb;
using System.Data.SqlClient;
Here:
static void Main(string[] args)
{
SqlConnectionStringBuilder cstrbuilder = new SqlConnectionStringBuilder();
cstrbuilder.DataSource = "localhost";
cstrbuilder.UserID = "frogmorton";
cstrbuilder.Password = "lillypad99";
cstrbuilder.InitialCatalog = "Dogs";
SqlConnection sconn = new SqlConnection(cstrbuilder.ToString());
sconn.Open();
SqlCommand scmd = new SqlCommand("select * from Dogs", sconn);
SqlDataReader reader = scmd.ExecuteReader();
if (reader.HasRows)
{
OleDbConnectionStringBuilder sb = new OleDbConnectionStringBuilder();
sb.Provider = "Microsoft.Jet.OLEDB.4.0";
sb.PersistSecurityInfo = false;
sb.DataSource = #"C:\A\StackOverflog\DogBase.mdb";
OleDbConnection conn = new OleDbConnection(sb.ToString());
conn.Open();
OleDbCommand cmd = new OleDbCommand("Delete from Dogs", conn);
cmd.CommandType = CommandType.Text;
cmd.ExecuteNonQuery();
conn.Close();
OleDbConnection conn2 = new OleDbConnection(sb.ToString());
conn2.Open();
OleDbCommand icmd = new OleDbCommand("Insert into dogs (DogID, DogName, Breed, Color) values ({0}, '{1}', '{2}', '{3}');", conn2);
icmd.CommandType = CommandType.Text;
while (reader.Read())
{
string insertCommandString =
String.Format("Insert into dogs (DogID, DogName, Breed, Color) values ({0}, '{1}', '{2}', '{3}');"
, reader.GetInt32(0)
, reader.GetString(1)
, reader.GetString(2)
, reader.GetString(3)
);
icmd.CommandText = insertCommandString;
icmd.ExecuteNonQuery();
}
conn2.Close();
}
sconn.Close();
}
The best way to do this is via PInvoke You will need to pass the CREATE_DBV3 parameter to SqlConfigDataSource(). Here is the code taken from JetSqlUtil.cs of my OSS Project PlaneDisaster.NET:
#region PInvoke
private enum ODBC_Constants : int {
ODBC_ADD_DSN = 1,
ODBC_CONFIG_DSN,
ODBC_REMOVE_DSN,
ODBC_ADD_SYS_DSN,
ODBC_CONFIG_SYS_DSN,
ODBC_REMOVE_SYS_DSN,
ODBC_REMOVE_DEFAULT_DSN,
}
private enum SQL_RETURN_CODE : int
{
SQL_ERROR = -1,
SQL_INVALID_HANDLE = -2,
SQL_SUCCESS = 0,
SQL_SUCCESS_WITH_INFO = 1,
SQL_STILL_EXECUTING = 2,
SQL_NEED_DATA = 99,
SQL_NO_DATA = 100
}
[DllImport("ODBCCP32.DLL",CharSet=CharSet.Unicode, SetLastError=true)]
private static extern int SQLConfigDataSource (int hwndParent, ODBC_Constants fRequest, string lpszDriver, string lpszAttributes);
[DllImport("ODBCCP32.DLL", CharSet = CharSet.Auto)]
private static extern SQL_RETURN_CODE SQLInstallerError(int iError, ref int pfErrorCode, StringBuilder lpszErrorMsg, int cbErrorMsgMax, ref int pcbErrorMsg);
#endregion
internal static string GetOdbcProviderName()
{
if (string.IsNullOrEmpty(OdbcProviderName))
{
var odbcRegKey = Registry.LocalMachine.OpenSubKey("SOFTWARE\\ODBC\\ODBCINST.INI\\ODBC Drivers", false);
var drivers = new List<string>(odbcRegKey.GetValueNames());
if (drivers.Contains("Microsoft Access Driver (*.mdb, *.accdb)"))
{
OdbcProviderName = "Microsoft Access Driver (*.mdb, *.accdb)";
}
else if (drivers.Contains("Microsoft Access Driver (*.mdb)"))
{
OdbcProviderName = "Microsoft Access Driver (*.mdb)";
}
else
{
//TODO: Condider checking for 32 versus 64 bit.
//TODO: Find a better exception type. http://stackoverflow.com/questions/7221703/what-is-the-proper-exception-to-throw-if-an-odbc-driver-cannot-be-found
throw new InvalidOperationException("Cannot find an ODBC driver for Microsoft Access. Please download the Microsoft Access Database Engine 2010 Redistributable. http://www.microsoft.com/download/en/details.aspx?id=13255");
}
}
/// <summary>
/// Creates an Access 2003 database. If the filename specified exists it is
/// overwritten.
/// </summary>
/// <param name="fileName">The name of the databse to create.</param>
/// <param name="version">The version of the database to create.</param>
public static void CreateMDB (string fileName, AccessDbVersion version = AccessDbVersion.Access2003) {
;
if (File.Exists(fileName)) {
File.Delete(fileName);
}
string command = "";
switch (version)
{
case AccessDbVersion.Access95:
command = "CREATE_DBV3";
break;
case AccessDbVersion.Access2000:
command = "CREATE_DBV4";
break;
case AccessDbVersion.Access2003:
command = "CREATE_DB";
break;
}
string attributes = String.Format("{0}=\"{1}\" General\0", command, fileName);
int retCode = SQLConfigDataSource
(0, ODBC_Constants.ODBC_ADD_DSN,
GetOdbcProviderName(), attributes);
if (retCode == 0)
{
int errorCode = 0 ;
int resizeErrorMesg = 0 ;
var sbError = new StringBuilder(512);
SQLInstallerError(1, ref errorCode, sbError, sbError.MaxCapacity, ref resizeErrorMesg);
throw new ApplicationException(string.Format("Cannot create file: {0}. Error: {1}", fileName, sbError));
}
}
If you need to do this from a 64 bit version of SQL server you will need the 64 bit version of Office 2010 or the Microsoft Access Database Engine 2010 Redistributable installed.
I think it's crazy to do it from SQL Server. Just create an ODBC DSN for your SQL Server and import the tables into your Access 97 MDB and be done with it. The only reason you might want to do it otherwise is if you want to automate it and do it repeatedly, but that can be automated in Access, too (TransferDatabase can do ODBC imports), and will take only as many lines of code as there are tables to import.