Extract table data into a merge statement without a unique column

/*
	This script extracts the existing data in a table
	and places it into a merge statement to allow the 
	table to be populated with the same data.

	This template will work with tables that do NOT have a single column to uniquely identify a row.
	Instead, it copies all the data to a temp table with a unique row identifier.

	select * from dbo.MyTable
*/

-- specify the name of the table whose data is to be output
:setvar TableName2 "dbo.MyTable"

-- specify any column name here. Picking the 1st column in the table is fine.
:setvar FirstColumn "ColNum1"

-- set a variable that specifies the name of the row number column in our temp table that we create.
-- if the source table already has a column with this exact same name, change this variable so that it is unique.
:setvar RowNumColumn "RowNumb"

GO
:on error exit
GO

/*
Detect SQLCMD mode and disable script execution if SQLCMD mode is not supported.
To re-enable the script after enabling SQLCMD mode, execute the following:
SET NOEXEC OFF; 
*/
:setvar __IsSqlCmdEnabled "True"
GO
IF N'$(__IsSqlCmdEnabled)' NOT LIKE N'True'
BEGIN
    PRINT N'SQLCMD mode must be enabled to successfully execute this script.';
	raiserror('SQLCMD mode must be enabled to successfully execute this script.', 20, -1) with log
    SET NOEXEC ON;
END

-- drop the source data temp table, if it exists.
IF (OBJECT_ID('tempdb..#SourceData') IS NOT NULL)
begin
    DROP TABLE #SourceData
end

-- make sure the temp table does not already exist
IF (OBJECT_ID('tempdb..#TempData') IS NOT NULL)
begin
    DROP TABLE #TempData
end
GO

GO

-- create a temp table 
CREATE TABLE #TempData
(
	lColOrder int not null primary key
	, sName varchar(255) not null
	, bIsIdentity bit not null default(0)
	, DataTypeId int not null
	, bUseTicks bit not null default(0)
	, ColData varchar(max) null	--not null default('null')

	, unique (sName, lColOrder)
)
GO

-- populate the #SourceData temp table.
print 'populate the #SourceData temp table'
SELECT 
	$(RowNumColumn) = row_number() over (order by $(FirstColumn))
	, a.*
into #SourceData
from $(TableName2) a

-- turn on nocount.
set nocount on;

-- insert the table columns into our temp table.
INSERT into #TempData
(lColOrder, sName, bIsIdentity, DataTypeId )
select column_id, [name], a.is_identity, system_type_id
from tempdb.sys.columns a
where a.[object_id] = object_Id('tempdb..#SourceData')
	and a.is_computed = 0
	--and (a.is_identity = 0 or $(IncludeIdentity) = 1)
	and a.system_type_id <> 189	-- exclude rowversion columns.
	and a.[name] <> '$(RowNumColumn)'
	--
	--and a.column_id <= 4	-- 9
	
-- get the smallest ColOrder value
declare @lFirstColOrder int
set @lFirstColOrder = (
	select top 1 lColOrder from #TempData order by lColOrder
)

-- update the 'Use Ticks' column for the data types that need to be enclosed in single quote characters.
UPDATE #TempData set
	bUseTicks = 1
where DataTypeId in (167, 35, 175, 40, 41, 61, 36, 231)

-- declare a variable to use for our execute command statements.
declare @cmd varchar(max)

-- declare some variables we'll use a little later.
declare @sCurrentCol varchar(255)
	, @lDataType int
	, @RowID int
	, @lSrcRowCount int = 0

-- update the [ColData] column to be null for all rows.
UPDATE #TempData set ColData=null


-- declare a variable to hold the output line.
declare @sOutputLine varchar(max)
declare @crlf varchar(2) = char(13) + char(10)
	, @tab varchar(1) = char(9)
	
print 'Current database: ' + DB_NAME()
print ''
print ''

print '/*'
print ''
print '	delete from $(TableName2)'
print ''
print '*/' + @crlf + @crlf


-- start the CTE portion of the output
set @sOutputLine = ';with cteSrc as (
	SELECT *
	from ( values
		-- Source DB: [' + @@servername + '].[' + DB_NAME() + '] at ' + convert(varchar(40), getdate(), 109) + @crlf 
print @sOutputLine


-- declare & open the columns cursor.
DECLARE curColumns cursor scroll read_only for
	select a.sName, a.DataTypeID 
	from #TempData a 
	--where ( (a.bIsIdentity = 0) or ($(IncludeIdentity) = 1) )
	order by a.lColOrder
OPEN curColumns


DECLARE @lSourceRowCount int
	, @lCurrentSourceRow int;
SELECT @lSourceRowCount = max($(RowNumColumn))
	, @lCurrentSourceRow = min($(RowNumColumn))
from #SourceData


-- keep going while we're still pointing to a valid row number
WHILE (@lCurrentSourceRow <= @lSourceRowCount)
begin
	-- get the 1st row from the columns cursor.
	FETCH first from curColumns into @sCurrentCol, @lDataType

	-- increment our row count
	set @lSrcRowCount = @lSrcRowCount + 1

	-- keep going while the last fetch was good.
	WHILE (@@fetch_status = 0)
	begin
		-- build the command statement for the current column
		set @cmd = 
			case @lDataType
				-- if the output order is to be changed, do it here, at the '$(UniqueCol)' section in the text strings
				when 61 then
					'update #TempData set ColData=(select convert(varchar(255), ' + @sCurrentCol + ', 126) from (select ' + @sCurrentCol + ', rownumber = $(RowNumColumn) from #SourceData) a where a.rownumber = ' + convert(varchar, @lCurrentSourceRow) + ') where sName=''' + @sCurrentCol + ''''
				else
					'update #TempData set ColData=(select ' + @sCurrentCol + ' from (select ' + @sCurrentCol + ', rownumber = $(RowNumColumn) from #SourceData) a where a.rownumber = ' + convert(varchar, @lCurrentSourceRow) + ') where sName=''' + @sCurrentCol + ''''
			end
	
		--print @cmd
		exec (@cmd)

		-- get the next row from the cursor.
		FETCH next from curColumns into @sCurrentCol, @lDataType
	end

	-- set our null value text
	UPDATE #TempData set
		ColData = --'null'
			case 
				when ColData is null then 'null'
				else '''' + replace(ColData, '''', '''''') + ''''
			end
	where ColData is null or bUseTicks=1

	-- initialize the output line, depending on if this is the 1st line or not.
	if (@lSrcRowCount = 1)
	begin
		set @sOutputLine = @tab + @tab + '('
	end else begin
		set @sOutputLine = @tab + @tab + ', ('
	end

	-- build our output line of data
	SELECT @sOutputLine = @sOutputLine 
		+ case when a.rownumber > 1 then ', ' else '' end
		+ a.ColData
	from (
		select *
			, rownumber = row_number() over (order by b.lColOrder)
		from #TempData b		
		--where (b.bIsIdentity = 0 or $(IncludeIdentity) = 1)
	) a
	order by a.lColOrder

	-- tack on a close parenthesis at the end.
	set @sOutputLIne = @sOutputLine + ')'

	-- output the line we created.
	print @sOutputLine
	
	-- increment our source row index
	set @lCurrentSourceRow = @lCurrentSourceRow + 1
end

-- close & deallocate the columns cursor
CLOSE curColumns
DEALLOCATE curColumns

set @sOutputLine = @tab + ') as src('
SELECT @sOutputLine = @sOutputLine
	+ case when a.rownumber = 1 then '' else ', ' end
	+ '[' + a.sName + ']'
from ( 
	select *
		, rownumber = row_number() over (order by lColOrder)
	from #TempData b
	--where ( (b.bIsIdentity = 0) or ($(IncludeIdentity) = 1) )
) a
order by a.lColOrder

-- close the CTE portion of the output
set @sOutputLine = @sOutputLine + ')' + @crlf + ')'
print @sOutputLine
print '-- select * from cteSrc'

-- build the merge statement
print 'merge into $(TableName2) as dest -- target'
print 'using cteSrc as src on '
print @tab + '-- Add the necessary field comparisons here that will let us uniquely identify a row.'
print @tab + 'dest.XXXXXXXXXXXX = src.XXXXXXXXXXXX'
print @tab + 'and dest.YYYYYYYYYYYY = src.YYYYYYYYYYYY'
print 'when matched then -- on match update'
print 'update set '
print @tab + '-- Be sure to comment out the update on the columns that uniquely identify a row.'

-- build the update part of the merge statement
set @sOutputLine = ''
SELECT @sOutputLine = @sOutputLine
	+ case when a.RowNumber = 1 then @tab else @crlf + @tab + ', ' end
	+ 'dest.[' + a.sName + '] = src.[' + a.sName + ']'
from (
	select *
		, RowNumber = row_number() over (order by lColOrder)
	from #TempData b
) a
order by a.lColOrder
print @sOutputLine

-- build the insert part of the merge statement
print 'when not matched then -- insert missing'

-- create the comma separated list of columns.
set @sOutputLine = ''
SELECT @sOutputLine = @sOutputLine
	+ case when a.RowNumber = 1 then '' else ', ' end
	+ '[' + a.sName + ']'
from (
	select *
		, RowNumber = row_number() over (order by lColOrder)
	from #TempData b
) a
order by a.lColOrder

-- output the insert column & value list.
print @tab + 'insert (' + @sOutputLine + ')'
print @tab + 'values (' + @sOutputLine + ')'

print '--when not matched by source then delete -- Delete missing from source'
print ';'


--turn off the nocount
set nocount off;


--select * from #TempData

---- make sure the temp table does not already exist
--IF (OBJECT_ID('tempdb..#TempData') IS NOT NULL)
--begin
--    DROP TABLE #TempData
--end