SQL Server Compact error: Unable to load DLL 'sqlceme35.dll'. The specified module could not be found_问答_开发者

I'm developing a Windows Forms application using Visual Studio 2008 C# that uses an SQL Server Compact 3.5 database on the client. The client will most likely be 32 bit Windows XP or Windows Vista machines. I'm using a standard Windows Installer project that creates an MSI file and setup.exe to install the application on a client machine. I'm new to SQL Server Compact, so I haven't had to distribute a client database like this before now. When I run the setup.exe (on new Windows XP 32 bit with SP2 and Internet Explorer 7) it installs fine, but when I run the application I get this error:

Unable to load DLL 'sqlceme35.dll'. The specified module could not be found

I spent a few hours searching for this error already, but all I could find were issues relating to installing on 64 bit Windows and none relating to normal 32 bit that I'm using.

The install application copies the all the depen开发者_运维问答dent files that it found into the specified install directory, including the System.Data.SqlServerCe.dll file (assembly version 3.5.1.0). The database file is in a directory called 'data' off the application directory, and the connection string for it is

<add name="Tickets.ieOutlet.Properties.Settings.TicketsLocalConnectionString"         connectionString="Data Source=|DataDirectory|\data\TicketsLocal.sdf"  providerName="Microsoft.SqlServerCe.Client.3.5" />

Some questions I have:

Should the application be able to find the DLL file if it's in the same directory, that is, local to the application, or do I need to install it in the GAC? (If so, can I use the Windows Installer to install a DLL file in the GAC?)
Is there anything else I need to distribute with the application in order to use a SQL Server Compact database?
There are other DLL files also, such as MS interop for exporting data to Excel on the client. Do these need to be installed in the GAC or will locating them in the application directory suffice?

You don't need it to be in the GAC for SQL Server Compact to run, and it will pick them up from the application directory. There are several ways to deploy an SQL Server Compact project. The two main ways are:

Deploying the SQL Server Compact redistributable installer with your project, but this way is painful and also can be unistalled by the end user, or upgraded by Windows updates and breaking your application.
Including the DLL files in your application folder. Depending on the features of SQL Server Compact you are using (replication or whatever), there is a handful of DLL files to deploy in your application folder.

If you have SQL Server Compact installed on your machine, they are most likely located at "C:\Program Files\Microsoft SQL Server Compact Edition\v3.5". They can be added to the project in Visual Studio and then set their project output type to "copy always". And the main reference to System.Data.SqlServerCe that you have in your project references should have copy local set to true.

sqlceca35.dll
sqlcecompact35.dll
sqlceer35en.dll
sqlceoledb35.dll
sqlceqp35.dll
sqlcese35.dll

If you have these all set, then in your installer project all you have to include is the project output of this project and you're good. In my opinion this is the only way to go. It is a simple deployment, of a couple of files and you are in control of what DLL versions your application uses.

I hope that helps.

I had a similar problem, a Visual Studio 2008 Windows application targeting 32-bit Windows XP and Windows Vista that used SQL Server Compact 3.5 SP1 - that then got this error when installed on 64-bit Windows 7:

Unable to load DLL 'sqlceme35.dll'. The specified module could not be found

I was embedding an MSI for SQL Server Compact into the installer for the application.

Following this rather confused discussion on MSDN revealed that I needed to use the 64-bit MSI for SQL Server Compact on 64-bit machines. D'oh! That is, from page Microsoft SQL Server Compact 3.5 Service Pack 1 and Synchronization Services for ADO.NET version 1.0 Service Pack 1 for Windows Desktop I needed SSCERuntime-ENU-x64.msi rather than SSCERuntime-ENU-x86.msi for 64-bit machines.

How to: Deploy a SQL Server Compact Edition Database with an Application should help, at least with your first two questions.

In general, I think you should not install anything in the GAC for a single application.

The following provide a solution to the problem and an explanation also.