Multiple SQL column delete and create using Regex

I recently had a task to move a large number of columns from one table to another and as I'm not keen on writing out line after line of SQL I generated some with a bit of regex. Here is a C# script I put together in LINQPad to do the replace (but you could easily do them in notepad).

void Main()
{
    string sourceTable = "Table1";
    string sourceTableFK = "Table2Id";
    string targetTable = "Table2";
    string targetTablePK = "Id";

    Dictionary<string, string> columns = new Dictionary<string, string> { 
        { "ColumnA", @"NVARCHAR(255)"}, 
        { "ColumnB", @"DATETIME"},
        { "ColumnC", @"INT"}
    };

    string addReplace = "IF NOT EXISTS (SELECT * FROM SYS.COLUMNS WHERE Name = '$1' AND object_id = (SELECT object_id FROM sys.objects WHERE Name = '" + targetTable + "'))\r\nBEGIN\r\n\tALTER TABLE " + targetTable + "\r\n\tADD\t$1 $2\r\nEND\r\nGO";

    string migrateReplace = "IF EXISTS (SELECT * FROM SYS.COLUMNS WHERE Name = '$1' AND object_id = (SELECT object_id FROM sys.objects WHERE Name = '" + sourceTable + "'))\r\nBEGIN\r\n\tUPDATE "+ targetTable + "\r\n\tSET\t$1 = (SELECT $1 FROM " + sourceTable + " WHERE " + sourceTableFK + " = " + targetTable + "." + targetTablePK + ")\r\nEND\r\nGO";

    string dropReplace = "IF EXISTS (SELECT * FROM SYS.COLUMNS WHERE Name = '$1' AND object_id = (SELECT object_id FROM sys.objects WHERE Name = '" + sourceTable + "'))\r\nBEGIN\r\n\tALTER TABLE " + sourceTable + "\r\n\tDROP COLUMN $1\r\nEND\r\nGO";

    foreach (var column in columns)
    {
        Regex.Replace(string.Format("{0}|{1}", column.Key, column.Value), @"^([^\|]*)\|([^\|]*)$", addReplace).Dump();
        Regex.Replace(column.Key, @"^([a-zA-Z0-9]*)$", migrateReplace).Dump();
        // handle constraints here
        Regex.Replace(column.Key, @"^([a-zA-Z0-9]*)$", dropReplace).Dump();
    }
}

The generated SQL will:

1. Create the new column in TableB
2. Copy the data from TableA to TableB based on the relationship TableA.TableBId = TableB.Id
3. Drop the column in TableA

Note that this doesn't do anything with constraints so you may need to handle these yourself

Please feel free to use, share, amend and criticise.