Multi-user Access Through A Data-access Layer/remoting Server
Oct 30, 2007
Hi guys,
I've been developing desktop client-server and web apps and have used Access and SQL Server Standard most of the time.
I'm looking into using SQL CE, and had a few questions that I can't seem to get a clear picture on:
- The documentation for CE says that it supports 256 simultaneous connections and offers the Isolation levels, Transactions, Locking, etc with a 4GB DB. But most people say that CE is strictly a single-user DB and should not be used as a DB Server.
Could CE be extended for use as a multi-user DB Server by creating a custom server such as a .NET Remoting Server hosted through a Windows Service (or any other custom host) on a machine whereby the CE DB would run in-process with this server on the machine which would then be accessed by multiple users from multiple machines??
Clients PCs -> Server PC hosting Remoting Service -> ADO.NET -> SQL CE
- and further more can we use Enterprise Services (Serviced Components) to connect to SQL CE and further extend this model to offer a pure high-quality DB Server?
Clients PCs -> Server PC hosting Remoting Service -> Enterprise Services -> ADO.NET -> SQL CE
Seems quite doable to me, but I may be wrong..please let me know either ways
Thanks,
CP
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May 3, 2007
How can I access data to SQL server 2005 using Windows form application,ADO.net and .Net remoting?
Can anybody help me? please...
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Jun 19, 2007
I've been following Soctt Mitchell's tutorials on Data Access and in Tutorial 1 (Step 5) he suggests using SQL Subqueries in TableAdapters in order to pick up extra information for display using a datasource.
I have two tables for a gallery system I'm building. One called Photographs and one called MS_Photographs which has extra information about certain images. When reading the MS_Photograph data I also want to include a couple of fields from the related Photographs table. Rather than creating a table adapter just to pull this data I wanted to use the existing MS_Photographs adapter with a query such as...1 SELECT CAR_MAKE, CAR_MODEL,
2 (SELECT DATE_TAKEN
3 FROM PHOTOGRAPHS
4 WHERE (PHOTOGRAPH_ID = MS_PHOTOGRAPHS.PHOTOGRAPH_ID)) AS DATE_TAKEN,
5 (SELECT FORMAT
6 FROM PHOTOGRAPHS
7 WHERE (PHOTOGRAPH_ID = MS_PHOTOGRAPHS.PHOTOGRAPH_ID)) AS FORMAT,
8 (SELECT REFERENCE
9 FROM PHOTOGRAPHS
10 WHERE (PHOTOGRAPH_ID = MS_PHOTOGRAPHS.PHOTOGRAPH_ID)) AS REFERENCE,
11 DRIVER1, TEAM, GALLERY_ID, PHOTOGRAPH_ID
12 FROM MS_PHOTOGRAPHS
13 WHERE (GALLERY_ID = @GalleryID)
This works but I wanted to know if there's a way to get all of the fields using one subquery instead of three? I did try it but it gave me errors for everything I could think of.Is using a subquery like above the best way when you want this many fields from a secondary table or should I be using another approach. I'm using classes for the BLL as well and wondered if there's a way to do it at this stage instead?
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Mar 10, 2008
Hello, everybody.
In my web application, i'm using 2 tabels; Users(Username(PK), Pwd, Name, Deptid(FK)) n Dept(Deptid(PK), Deptname)).
For creating a Data Access Layer 4 my project, I added dataset as new item n followed the wizard 2 create the required functions.
I have a function GetUser(@uname, @pwd), which takes username n password as input. M using this for authentication purpose.
While executing it poping an ConstrainException.
Plz help me out.
I've tried 2 as clear as possible here. OR u may ask me any other questions for clear picture of the scenario.
Thanks and Regards,
Sankar.
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Jun 11, 2008
I request you plz tell how to create Data Access Layer. I mean DataAccess.dll. So that I can call stored procedure from dataaccess.dll as below.
DataAccess.SqlHelper.ExecuteDataset(DataAccess.DSN.Connection("DBConnectionString"), CommandType.StoredProcedure, "SP_GetEmpIds");
I request you how can I add this stored procedures to DataAccess.dll and function. I am not having any idea in this area. I request you plz give me some suggestions to work with task.
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Apr 5, 2007
How do I get a System Table like 'Sysobjects' into the Data Access Layer?
My app generates tables on the fly, and has to check in the sysobjects table which tables are present.
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Jan 10, 2008
Hi Experts ! I want to use maximum feature of SQL
Server 2005 and ASP.Net 2.0 in making Data Access LayerSuggestions will be welcomed .Thank you
RegardsKAMRAN
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Feb 20, 2008
I've a management module (managing Products) currently being displayed on the aspx page using ObjectDataSource and GridView control.The datasource is taken from a class residing in my Data Access layer with custom methods such as getProducts() and deleteProduct(int productID)I'm currently using SqlDataAdapter as well as Datasets to manipulate the data and have no big problems so far.However, my issue is this, each time i delete a product using the deleteProduct method, I would need to refill the dataset to fill the dataset before i can proceed to delete the product. But since I already filled the dataset using the getProducts() method, is it possible to just use that dataset again so that I dont have to make it refill again? I need to know this cos my data might be alot in the future and refilling the dataset might slow down the performance. 1 public int deleteCompany(Object companyId)
2 {
3 SqlCommand deleteCommand = new SqlCommand("DELETE FROM pg_Company WHERE CompanyId = @companyId", getSqlConnection());
4
5 SqlParameter p1 = new SqlParameter("@companyId", SqlDbType.UniqueIdentifier);
6 p1.Value = (Guid)companyId;
7 p1.Direction = ParameterDirection.Input;
8
9 deleteCommand.Parameters.Add(p1);
10 dataAdapter.DeleteCommand = deleteCommand;
11
12 companyDS = getCompanies(); // <--- I need to refill this before I can delete, I would be iterating an empty ds.
13
14 try
15 {
16 foreach (DataRow row in companyDS.Tables["pg_Company"].Select(@"companyId = '" + companyId + "'"))
17 {
18 row.Delete();
19 }
20 return dataAdapter.Update(companyDS.Tables["pg_Company"]);
21 }
22 catch
23 {
24 return 0;
25 }
26 finally { }
27 }
I thank you in advance for any help here.
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Jul 9, 2007
Hi,
I am having a application in which from the front end i am saving details of three different things
i.Enquiry Details
ii.Parts Details
iii.Machine details
i am saving the Enquiry detail in a data table,Parts Details in a data table and machine detail in a data table and finally i am adding the three data tables into a single data set and passing the data set to data access layer there i have three insert command one for each data table in my case the enquiry data table will be saved first and then the next two details will be saved and i am saving the details in three different tables in the database, my problem is some times the enquiry details will save to the database and while saving the Parts details there may be some exception and i will throw an exception in that case the enquiry details will be saved and the remaining two details are not saved(Which are also part of the same Transaction).I wanted to know about how to call the transaction function in case of Data Access Layer.
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Sep 27, 2007
in the class library i written the code name :customer is the lib name
using System;
using System.Collections.Generic;
using System.Text;
namespace Customer
{ class Entites
{
public int inTest;
public int inTest2;
}
}
Now in the Class1.cs i written the code
i am getting the data from the database by using enterprise lib 2006 connection function
now HOW TO BIND THE DATA TO LIST AND RETURN TYPE IS LIST
PLEASE CHECK THE CODE AND REDEFINE THE CODE
using System;
using System.Data ;
using System.Collections.Generic;
using System.Collections.Generic;
using System.Text;
using Microsoft.Practices.EnterpriseLibrary.Data;
using Microsoft.Practices.EnterpriseLibrary.ExceptionHandling;
using Microsoft.Practices.EnterpriseLibrary.Common.Configuration;
using System.Collections;
using System.Xml.Serialization;
using System.Data.Common;
using Customer;
namespace Customer
{
class Class1
{
public List<Entites> getdata(int id)
{
Database db = DatabaseFactory.CreateDatabase("mycon");
System.Data.Common.DbCommand cmd ;
cmd = db.GetStoredProcCommand("GET_CUSTOMER");
cmd.CommandType = CommandType.StoredProcedure;
db.AddInParameter(cmd,"@CID",System.Data.DbType.Int32,id);
List<Entites> objEntites = new List<Entites>();
using (IDataReader dr = db.ExecuteReader(cmd))
foreach (Entites obj in dr)
{
objEntites.inTest = obj.inTest;-----------------------------------------------ERROR LINE
// objEntites.Add(obj);
}
return objEntites;
}
}
}
Error 2 foreach statement cannot operate on variables of type 'System.Data.IDataReader' because 'System.Data.IDataReader' does not contain a public definition for 'GetEnumerator' D:KOTI_PRJSEnterpriseCustomerClass1.cs 34 13 Customer
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Sep 20, 2006
I am taking my first stab at a 3 tier architecture within ASP.Net. I have been adding datasets and creating a new Insert to add certain parts to a table. I am trying to add a date field called 'DateAdded' and is setup in SQL as a DateTime. When Visual Studio auto created the dataset, the Insert function is not "DateAdded as Datetime" as I would have expected, but it is "DateAdded as System.Nullable(Of Date)". There is a space in between 'Of' and 'Date'. If I keep the space in there the insert function shows an error that says "Arguement not specified for parameter DateAdded of funtion( etc. etc.). If I take the space out, the error on the insert function goes away but there is an error within the "OfDate" that says "Array bound cannot appear in type specifiers". I am confused on why the date format changed and how I can get a date to go into the database using the autogenerated datasets from Visual Studio. Any help would be appreciated. Thanks, Mike
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Nov 1, 2006
HiI'm having problems following the tutorial on creating a data access layer - http://www.asp.net/learn/dataaccess/tutorial01cs.aspx?tabid=63 - when I try to compile in Visual Studio 2005 I get namespace could not be found. I followed exactly the tutorial - I created a dataset and added this code in my aspx page. <asp:GridView ID="GridView1" runat="server" CssClass="DataWebControlStyle"> <HeaderStyle CssClass="HeaderStyle" /> <AlternatingRowStyle CssClass="AlternatingRowStyle" />In my C# file I added these lines... using NorthwindTableAdapters; <<<<<this is the problem - where does this come from? protected void Page_Load(object sender, EventArgs e) { ProductsTableAdapter productsAdapter = new ProductsTableAdapter(); GridView1.DataSource = productsAdapter.GetProducts(); GridView1.DataBind(); }Thanks in advance
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May 19, 2008
Hello,
My datalayer of C# code is invoking a stored procedure that returns a varchar(max) SQL data type. In my ASP.NET code, I have:
SqlCommand myCommand = new SqlCommand("usp_GetTestString", myConnection);
myCommand.Parameters.Add(new SqlParameter("@TestString", SqlDbType.Text));
myCommand.Parameters["@TestString"].Direction = ParameterDirection.Output;
myConnection.Open();
myCommand.ExecuteNonQuery();
return Convert.ToString(myCommand.Parameters["@TestString"].Value);
The query fails to execute and returns an error: String[1]: the Size property has an invalid size of 0. If I change the SqlDbType.Text parameter type to SqlDBType.Varchar, 100 (or any other fixed varchar length), it works but limits the length my unlimited field text. Any suggestions on how I can use db type text or varchar(max)? The field I need to retrieve is string characters of unlimited length and
hence the datatype varchar(max).
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Oct 25, 2006
I have developed two programs that operates against the same database. One of the program is just a display program that displayes the data put into the other administation program where you put in the data to be displayed (an administration program).
Every time I access the db from the administration program, the display program stops and throws connection pool errors and other database errors. For me, it looks like it does´t do multi-access to a database.
I have tried putting user instance to off in both programs, but this didn´t help.
Connection string also points to same file database.
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Sep 11, 2007
Please help....
I have designed an application that uses sql server 2005 express database. This application was intended to be installed and used on a local desktop machine. However, now this application needs to be also installed on several computers and still needs to use only 1 database. Part of the database saves local user settings, so what I have done thus far is use two connection strings: one for local database (because the application may be used as origionally intended) and one for remote database that everyone should be able to connect to.
When I remotely connect to the database, it works fine. However, it seems to be locked so when I chose the same database for another user I get the error message "This File Is In Use." I need to know how to unlock it and make it usable for several users at the same time.
Thank you for your help! Please let me know if you need more information or if something is unclear in my description.
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Feb 10, 2007
Of all the Visual Basic.NET data access books that I have purchased and all the Internet site example code that I have reviewed, none have had any good examples of multi-threaded VB.NET code doing data access.
I am trying to avoid the non-responsiveness in a VB app while a simple data retrieval from SQL Server 2005 is in progress.
If anyone knows of any book titles or web sites that have example code (good or not) of multi-threaded VB.NET applications doing data access against Microsoft SQL Server (7, 2000, or 2005) or even against Microsoft Access(TM), it would be very much appreciated if you could provide the book title or URL to point me in the right direction.
The more examples the better.
Thanks in advance.
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Apr 8, 2007
Before page 12, step by step instructions work!
Then there is code for AllProducts.aspx that doesn't work if one inserts the code
into the DataTutorial project started on page 1. Yes I changed the name of the CodeFile!
The code given for AllProducts.aspx.cs doesn't compile.
I was doing better without the tutorial!
I can gleen out some concepts but that is all.
If that is all, why have a tutorial?
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Sep 20, 2006
I am in the process of migrating 40 access databases to SQL Server and still use an access front end.All of these databases are Identical in structure and purpose. The goal is to centralize all of the databases backends into one Sql server database, but the data needs to
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Mar 21, 2014
I have a windows 2008 with SQL Server 2008 R2 VM on Azure. I am trying to connect to the SQL server for the first time using SSMS, but have not been able it. I have a VPN tunnel, so I am connecting using Windows authentication. The error I get back from SSMS is:
Login failed for user 'domainusername'. (Microsoft SQL Server, Error: 18456).In the event viewer I see this error message: Login failed for user 'domainusername'. Reason: Token-based server access validation failed with an infrastructure error. Check for previous errors. [CLIENT: <local machine>]
I have done the following:
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Jun 10, 2015
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I also cannot create any new queries and get the same error message. If I log on as myself on the domain to another PC with 2007 installed it works fine, so I don't think it is anything to do with AD groups or permissions.
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Jun 17, 2007
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Mar 25, 2008
I need to determine the following about the current authenticated Windows domain user who is trying to access a SQL Server via a trusted connection.
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3 Is the current user a member of a specific database role such as (DB_ROLE_ADMINISTRATORS)?
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Sep 10, 2015
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ssrs2014
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Dec 6, 2013
I would like to know if there is a way to find out who changed a users roles/access WITHOUT using the audit function. For example, if a user account was created and given SA access then changed to read only, how can I find out who made that change? I tried searching for an answer, but kept getting no results. I'm thinking this may tie into the sys.sysusers view?
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Jul 13, 2015
I'm using a legacy application built using VB5 and SQL Server 7. After recompiling it, and putting the database in SQL Server 2012. I want to access the current login user using the SQL function SUSER_SNAME().
This is the code.
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Mar 3, 2008
When creating a user control (ascx) and registering it in the webpage, an error occurred:
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Sep 22, 2015
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SET QUOTED_IDENTIFIER ON
[code]....
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Dec 11, 2006
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Oct 3, 2006
I'm hoping someone can get me pointed in the right direction
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can any one help
thanks
David
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Jul 28, 2015
How do I grant a user permissions to only one table in a database.  How would it affect him using our Main App which is NAV with regards to his user's permission in NAV
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Jun 9, 2015
When i wanna run Application in other computers in network. The following error occurs.
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Nov 12, 2015
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