CS0246: The type or namespace name 'DataSet' could not be found

[danpe]

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;

public class Helper
{
    static public DataSet GetDataSet(string strSql)
    {
        DataSet ds = new DataSet();
        SqlConnection connection = new SqlConnection(ConnectionString());
        SqlCommand command = new SqlCommand(strSql, connection);
        SqlDataAdapter dataAdapter = new SqlDataAdapter(strSql, connection);
        dataAdapter.Fill(ds, "tblUsers");
        return ds;
    }
}

and i get this error:

CS0246: The type or namespace name 'DataSet' could not be found (are you missing a using directive or an assembly reference?)

It used to work i dont know what heppend...

[mariocatch]

This means the type (in this case, DataSet) can not be found within the imported namespaces for your namespace).

If you're using Visual Studio IDE, right click on the DataSet type in your IDE. Go to resolve, and select either option there (add using or implement explicitly).

This will either add the namespace up top in your using statements, or it will add it explicitly to the DataSet usage in-code for you.

[eclipsed4utoo]

Check for the System.Data reference in the reference list. It should be added by default, but it could have been removed.

[danpe]

Check for the System.Data reference in the reference list. It should be added by default, but it could have been removed.

Thanks it works

but now i have a new error

The expression prefix 'ConnectionStrings' was not recognized.  Please correct the prefix or register the prefix in the <expressionBuilders> section of configuration.

[mariocatch]

See MSDN for proper usage of connectionStrings tags in app.config files:

http://msdn.microsoft.com/en-us/libr...94(VS.80).aspx

[danpe]

its correct..

<connectionStrings>
    <clear />
		<add name="ConnectionString2" connectionString="Data Source=ihostedresource.com;Initial Catalog=illusionvwdb;Persist Security Info=True;User ID=illusionvwdb;Password=*****" providerName="System.Data.SqlClient" />
	</connectionStrings>

[mariocatch]

is it in a <configuration> group? is this for a webpage? what's the context?

[danpe]

its in the web.config file
and its inside the <configuration> tags...

[mariocatch]

i can keep asking you questions and get one line responses, or you can give us more details of the problem. perhaps the entire config file?

[danpe]

<?xml version="1.0"?>
<!-- 
    Note: As an alternative to hand editing this file you can use the 
    web admin tool to configure settings for your application. Use
    the Website->Asp.Net Configuration option in Visual Studio.
    A full list of settings and comments can be found in 
    machine.config.comments usually located in 
    \Windows\Microsoft.Net\Framework\v2.x\Config 
-->
<configuration>
	<configSections>
		<sectionGroup name="system.web.extensions" type="System.Web.Configuration.SystemWebExtensionsSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
			<sectionGroup name="scripting" type="System.Web.Configuration.ScriptingSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
				<section name="scriptResourceHandler" type="System.Web.Configuration.ScriptingScriptResourceHandlerSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/>
				<sectionGroup name="webServices" type="System.Web.Configuration.ScriptingWebServicesSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
					<section name="jsonSerialization" type="System.Web.Configuration.ScriptingJsonSerializationSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="Everywhere"/>
					<section name="profileService" type="System.Web.Configuration.ScriptingProfileServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/>
					<section name="authenticationService" type="System.Web.Configuration.ScriptingAuthenticationServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/>
					<section name="roleService" type="System.Web.Configuration.ScriptingRoleServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/>
				</sectionGroup>
			</sectionGroup>
		</sectionGroup>
	</configSections>
	<appSettings/>
	<connectionStrings>
		<clear/>
		<add name="ConnectionString2" connectionString="Data Source=ihostedresource.com;Initial Catalog=illusionvwdb;Persist Security Info=True;User ID=illusionvwdb;Password=*****" providerName="System.Data.SqlClient"/>
	</connectionStrings>
	<system.web>
		<!-- 
            Set compilation debug="true" to insert debugging 
            symbols into the compiled page. Because this 
            affects performance, set this value to true only 
            during development.

            Visual Basic options:
            Set strict="true" to disallow all data type conversions 
            where data loss can occur. 
            Set explicit="true" to force declaration of all variables.
        -->
		<compilation debug="true" strict="false" explicit="true">
			<buildProviders>
				<add extension=".aspx" type="System.Web.Compilation.PageBuildProvider"/>
				<add extension=".ascx" type="System.Web.Compilation.UserControlBuildProvider"/>
				<add extension=".master" type="System.Web.Compilation.MasterPageBuildProvider"/>
				<add extension=".asmx" type="System.Web.Compilation.WebServiceBuildProvider"/>
				<add extension=".ashx" type="System.Web.Compilation.WebHandlerBuildProvider"/>
				<add extension=".soap" type="System.Web.Compilation.WebServiceBuildProvider"/>
				<add extension=".resx" type="System.Web.Compilation.ResXBuildProvider"/>
				<add extension=".resources" type="System.Web.Compilation.ResourcesBuildProvider"/>
				<add extension=".wsdl" type="System.Web.Compilation.WsdlBuildProvider"/>
				<add extension=".xsd" type="System.Web.Compilation.XsdBuildProvider"/>
				<add extension=".js" type="System.Web.Compilation.ForceCopyBuildProvider"/>
				<add extension=".lic" type="System.Web.Compilation.IgnoreFileBuildProvider"/>
				<add extension=".licx" type="System.Web.Compilation.IgnoreFileBuildProvider"/>
				<add extension=".exclude" type="System.Web.Compilation.IgnoreFileBuildProvider"/>
				<add extension=".refresh" type="System.Web.Compilation.IgnoreFileBuildProvider"/>
			</buildProviders>
			<assemblies>
				<add assembly="Recaptcha"/>
				<add assembly="System.Core, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
				<add assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
				<add assembly="System.Data.DataSetExtensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
				<add assembly="System.Xml.Linq, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
				<add assembly="System.Web.DynamicData, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
				<add assembly="System.Web.Routing, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
				<add assembly="System.Web.Abstractions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
				<add assembly="System.ComponentModel.DataAnnotations, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
				<add assembly="System.Data.Linq, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
				<add assembly="System.Data.Entity, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
				<add assembly="System.Web.Extensions.Design, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
				<add assembly="System.Design, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/>
				<add assembly="System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
				<add assembly="System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
				<add assembly="System.Xml, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
			</assemblies>
		</compilation>
		<pages>
			<namespaces>
				<clear/>
				<add namespace="System"/>
				<add namespace="System.Collections"/>
				<add namespace="System.Collections.Generic"/>
				<add namespace="System.Collections.Specialized"/>
				<add namespace="System.Configuration"/>
				<add namespace="System.Text"/>
				<add namespace="System.Text.RegularExpressions"/>
				<add namespace="System.Linq"/>
				<add namespace="System.Xml.Linq"/>
				<add namespace="System.Web"/>
				<add namespace="System.Web.Caching"/>
				<add namespace="System.Web.SessionState"/>
				<add namespace="System.Web.Security"/>
				<add namespace="System.Web.Profile"/>
				<add namespace="System.Web.UI"/>
				<add namespace="System.Web.UI.WebControls"/>
				<add namespace="System.Web.UI.WebControls.WebParts"/>
				<add namespace="System.Web.UI.HtmlControls"/>
			</namespaces>
			<controls>
				<add tagPrefix="asp" namespace="System.Web.UI" assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
				<add tagPrefix="asp" namespace="System.Web.UI.WebControls" assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
			</controls>
		</pages>
		<!--
            The <authentication> section enables configuration 
            of the security authentication mode used by 
            ASP.NET to identify an incoming user. 
        -->
		<authentication mode="Windows"/>
		<!--
            The <customErrors> section enables configuration 
            of what to do if/when an unhandled error occurs 
            during the execution of a request. Specifically, 
            it enables developers to configure html error pages 
            to be displayed in place of a error stack trace.

        -->
		<customErrors mode="Off"/>
		<httpHandlers>
			<remove verb="*" path="*.asmx"/>
			<add verb="*" path="*.asmx" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
			<add verb="*" path="*_AppService.axd" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
			<add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" validate="false"/>
		</httpHandlers>
		<httpModules>
			<add name="ScriptModule" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
		</httpModules>
	</system.web>
	<system.codedom>
		<compilers>
			<compiler language="c#;cs;csharp" extension=".cs" warningLevel="4" type="Microsoft.CSharp.CSharpCodeProvider, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
				<providerOption name="CompilerVersion" value="v3.5"/>
				<providerOption name="WarnAsError" value="false"/>
			</compiler>
			<compiler language="vb;vbs;visualbasic;vbscript" extension=".vb" warningLevel="4" type="Microsoft.VisualBasic.VBCodeProvider, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
				<providerOption name="CompilerVersion" value="v3.5"/>
				<providerOption name="OptionInfer" value="true"/>
				<providerOption name="WarnAsError" value="false"/>
			</compiler>
		</compilers>
	</system.codedom>
	<!-- 
        The system.webServer section is required for running ASP.NET AJAX under Internet
        Information Services 7.0.  It is not necessary for previous version of IIS.
    -->
	<system.webServer>
		<validation validateIntegratedModeConfiguration="false"/>
		<modules>
			<remove name="ScriptModule"/>
			<add name="ScriptModule" preCondition="managedHandler" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
		</modules>
		<handlers>
			<remove name="WebServiceHandlerFactory-Integrated"/>
			<remove name="ScriptHandlerFactory"/>
			<remove name="ScriptHandlerFactoryAppServices"/>
			<remove name="ScriptResource"/>
			<add name="ScriptHandlerFactory" verb="*" path="*.asmx" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
			<add name="ScriptHandlerFactoryAppServices" verb="*" path="*_AppService.axd" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
			<add name="ScriptResource" preCondition="integratedMode" verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
		</handlers>
	</system.webServer>
	<runtime>
		<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
			<dependentAssembly>
				<assemblyIdentity name="System.Web.Extensions" publicKeyToken="31bf3856ad364e35"/>
				<bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="3.5.0.0"/>
			</dependentAssembly>
			<dependentAssembly>
				<assemblyIdentity name="System.Web.Extensions.Design" publicKeyToken="31bf3856ad364e35"/>
				<bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="3.5.0.0"/>
			</dependentAssembly>
		</assemblyBinding>
	</runtime>
</configuration>

[QuinnJohns]

per...

<add name="ConnectionString2" connectionString="Data Source=ihostedresource.com;Initial Catalog=illusionvwdb;Persist Security Info=True;User ID=illusionvwdb;Password=*****" providerName="System.Data.SqlClient"/>

try this...

SqlConnection connection = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString2"].ToString());

Let me know if it works!

H2H,
-Quinn

If it works, feel free to rate up!