Altering Collumn Values and data type properties (SQL Server 2005)

I have undertaken a Data Warehousing project. I am using the SQL Server Business Intelligence 2005 and Visual Studio 2005 to achieve my goals.

As of now, I have managed to extract data from a few flat files and loaded them in a relational table by mapping collumns from the flat files to the output table.

I have the following questions:

1) How do you update a certain collumn with new values by replacing the old ones simply by referencing the specific row numbers that I can visually see. For example I would like to replace all values from the collumn "name" and row number 1-23 with "Barry". Can this be done using a simple SQL "Update" statement.

2) Can I alter the properties of a collumn. For example, I would like change the data type of collumn from VARCHAR(50) to integer, decimal or float.

3) Can I use regular expressions in SQL statements to change the structure of data within certain collumns. This is a transformation process.

If you are getting a drift of what I am trying to accomplish from the above description, please feel free to suggest better and more efficient ways to accomplish the same task. However, I would like to accomplish everything within the SQL Server Business Intelligence tool 2005 and Visual Studio 2005 environment.


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1) Have a look at Row_Number(). Note that this is a Bad Idea.

2) Alter Table ... Alter Column ... Int / Dec / Float


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