This is one of the most common errors occurring when installing SQL Server Express 2005. This error occurs in different scenarios on different machine configurations.

One solution that works in all or most of the cases is to uninstall MSXML 6.0 and then install SQL Server. But this solution is not trivial either. Because, you cannot uninstall MSXML 6.0 from add/remove programs. Microsoft had published an utility called (msicuu2.exe) but they have recently removed this utility and I could not find any reliable source to download it from.

There is however a tool msizap that you can download and then use the following command to uninstall MSXML 6.0.

MsiZap T! {1A528690-6A2D-4BC5-B143-8C4AE8D19D96}

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If you package SQL Server with you application, then you can put this command in the batch file and even automate this process.

There is also scenario where above command does not work. In that case i would suggest using some Install Cleanup utility. One of the tools that i have used and works quite well is Your Uninstaller.

An embedded database is a database management system (DBMS) which is tightly integrated with an application software. They do not require any separate installation and are hidden from the end user.

I recently consulted on a project to replace SQL Server with a lightweight embedded database. We had however kept our option open and were also looking at databases with less installation hiccups – the main motivation to get rid of SQL Server.

There are many embedded databases available today and to filter out the one you need its important to have some criteria. Following are the list of things we were looking for in the target database:

• No Installation Required (Preferably)

• SQL based.

• Performance should be as good as possible to SQL Server.

• RDBMS (So that we have less overhead when migrating from SQL Server)

• Can work in Server as well as embedded mode.

• Supports Stored Procedures (Not mandatory but good to have)

• Has .NET data access API.

• Costs reasonable for desktop applications with unlimited installation.

• Some renowned companies using them. This is to judge the stability.

• Easy migration path from SQL Server

Many of the requirements as you can see are for the sake of less overhead when we migrate from SQL Server. I went through many databases to find the one we needed. Many of the databases did not fit into our criteria just because they were not RDBMS or they didn’t have .NET APIs. Following databases are either non RDBMS or don’t have .NET APIs:

• MongoDB

• Casandra

• CouchDB

• Apache Derby

• Raima Database Manager

• SolidDB

• Oracle Berkley DB

• Valentina DB (ORDBMS)

• Informix Dynamic Server

Now, i will discuss the ones i really looked into.

• Firebird

• Both embedded and server flavors.

• RDBMS

• Has .NET data provider APIs.

• Stable. Built on the InterBase source code.

• Used by many companies. Lots of resources available on the web.

• Switching between server and embedded version mostly require change of connection string only.

• Supports stored procedures.

• Supports standard SQL.

• Performance is close to SQL Server.

• Open Source. Free for development and distribution.

Scimore DB

• Both embedded and server flavors. In the embedded version, they can even be configured to run in-process and out-of-process.

• RDBMS.

• Has .NET data provider APIs.

• Not very stable.

• No big name associated. Tough to find resources on the web.

• Switching between server and embedded mostly require change of connection string only.

• Supports stored procedures.

• Supports standard SQL.

• Performance is close to SQL Server.

• Free for development and distribution. Source code is also available at reasonable cost.

Elevate DB

• Both embedded and server flavors.

• RDBMS.

• Has .NET APIs.

• Supports stored procedures.

• Support standard SQL.

• No big names associated.

• Performance is slower than SQL Server.

ITTIA DB

• Embedded and server flavors.

• RDBMS

• Has .NET APIs.

• No stored procedures (It was supposed to be coming soon, i haven’t checked)

• Supports standard SQL.

• No big names associated.

• Performance is slower than SQL Server.

Effiproz

• Only embedded.

• RDBMS

• Has .NET APIs.

• Supports stored procedures.

• Free (MSPL)

SQL CE

• Only embedded

• RDBMS

• Has .NET APIs

• No stored procedures

• Free for distribution

• Supports standard SQL

• Performance of SELECT queries is considerably slower than SQL Server for large databases.

SQLite

• Only embedded

• RDBMS

• Has .NET APIs

• No stored procedures.

• Free for development and distribution

• Supports standard SQL

• Many big companies using it. Stable.

• Performance of SELECT queries is slower than SQL Server for large databases.

Vista DB

• Only embedded

• RDBMS

• Has .NET API. In fact, the database itself is in managed code.

• Supports stored procedures.

• Supports standard SQL.

• Performance is slower than SQL Server.

Empress Embedded Database

• Only embedded.

• RDBMS.

• Has .NET APIs.

• Supports stored procedure.

• Supports standard SQL

• Performance is slower than SQL Server.

InterBase

• Embedded edition only ideal for MySQL

• Not embedded

• RDBMS

• Has .NET API

• Supports stored procedures

• Supports standard SQL

• Performance is close to SQL Server.

• Not free when your application is not open.

Note that some databases might have enhanced their features so i would also suggest to check their latest set of supported features for any enhancements they might have come up with.

string fileName = @"C:\ReadOnlyFile.txt";
File.SetAttributes(fileName, File.GetAttributes(fileName) & ~FileAttributes.ReadOnly);

Above C# code ensures that fileName does not have ReadOnly attribute set. SetAttribute static method takes fileName as the first parameter and FileAttributes enumeration as the second parameter. FileAttributes is a Flags enumeration meaning that we can combine multiple FlagAttributes values and set that as attribute of the file.

In the above code, we derive the FileAttributes to set by getting actual file attribute and doing a bitwise AND (operator &) with complement (operator ~) of ReadOnly attribute. This ensures that ReadOnly bit is set to zero leaving all the other attributes of the file as they were.

If you are unclear about logical operators, look at the following link for details:

http://msdn.microsoft.com/en-us/library/6a71f45d(VS.71).aspx

I needed that when i saw that even after i had uninstalled SQL Server from my machine, the service was still showing in Windows services. This is a sign that SQL was not uninstalled correctly and some of the pieces are still lying around. In this case you have to manually delete the service and do the file system and registry cleanup.

Windows has a command line utility called “sc” (I assume it stands for Service Controller) that gives us the APIs to talk to Windows services. Following command deletes SQLExpress service from the computer, for example.

sc delete MSSQL$SQLExpress

To know the actual name of the service, you can go to the properties (Right click and select properties) of that service from Windows Services window (Start—>Run—>Services.msc) and check the service name.

Here, I am going to present a very compact recursive c# code to compute all the permutations of a given string. Look at the following c# method:

public void PrintPermutations(string stringToPermute, string prefix)
{
   if (stringToPermute.Length <= 0)
   {
       Debug.WriteLine(prefix);
   }
   else
   {
       for(int i=0;i<stringToPermute.Length;i++)
           PrintPermutations(stringToPermute.Replace(stringToPermute[i].ToString(), ""), prefix + stringToPermute[i]);
   }
}

To find all the permutations of the string “ABC”, for example, you will call the method as follows: PrintPermutations(“ABC”, “”); Also note that, I assume that stringToPermute parameter is a string containing non-repeating characters.

Often in the batch script we need to change to the directory from where the batch file is executing. Mainly when you are shipping the batch file with your application, you may want to launch some executable from the batch file, for example. So, if you put batch file where the executable is, following batch script will do the job for you: cd %~dp0MyApplication.exe First statement changes current directory to the location of batch file and then second statement launches the application.

Many a time we run into requirement of executing simple SQL scripts using command prompt. Microsoft gives us a utility called “sqlcmd” just for that. Following is a very simple query executed using this tool: sqlcmd -S .\SQLEXPRESS -E -Q “Drop Database SampleDB” Where SampleDB is the database name i want to drop, -S switch specifies the server instance, -E switch specifies that i want to use trusted connection and -Q switch specifies the SQL query i want to execute. This tool is quite powerful and there are several switches that you can use to meet different requirements. You can open command prompt and see help (sqlcmd /?) for all the different switches that it supports.