Common, but not the best.  You'll hurt your overall performance significantly this way.

These...

You don't need or want the dashes in the date:

SELECT STUFF(STUFF(STUFF(main_datetime, 13, 0, ':'), 11, 0, ':'), 9, 0, ' ') + '.0000000' AS datetime2_format,

USE database_name;
ALTER DATABASE database_name SET SINGLE_USER;
DBCC CHECKDB ( database_name, REPAIR_REBUILD );
ALTER DATABASE database_name SET MULTI_USER;

Check for a way to override the data type to be bigint (or even int, if you know that will hold all the values) instead of float(53).

I'd certainly try to fix it without allowing SQL to lose any data.  If it can fix it cleanly, why leave it bad?

Something like this should do it:

.
SELECT t1.CreateDate, t2.CreateDate, DATEDIFF(MONTH, t1.CreateDate, t2.CreateDate), t1.AtNumber, t1.HFK
FROM Table_1 t1
LEFT OUTER JOIN (
  SELECT *, ROW_NUMBER() OVER(PARTITION...

Or, if you want to allow @VisitID to be specified but not to require it:

ALTER procedure [dbo].[spRadialAnalyticsDataExtract_ADLAssessment]
(
@AccountNumber varchar(30),
@VisitID varchar(30) = NULL
)

If you just want a count of the common attributes, you could do this:

SELECT RT1.ReportName AS ReportA, RT2.ReportName AS ReportB, COUNT(*) AS CommonAttributesCount
FROM ReportTable RT1
INNER JOIN...


SELECT RT1.ReportName AS ReportA, RT2.ReportName AS ReportB, RT1.AttributeName AS AttributeInCommon
FROM ReportTable RT1
INNER JOIN ReportTable RT2 ON RT2.ReportName > RT1.ReportName AND RT2.AttributeName = RT1.AttributeName

If you'll post some directly useable data -- CREATE TABLE and INSERT statements -- I'll provide you code to do this (or someone else will first).

You'll need an abstract that represents any legal entity about which you need to store information.  In this case, so far that's company or shareholder.

Legal_Entities ( Legal_Entity_Id, Name,...

Very sorry, sp_marksystemobject is my own version of the true MS proc.

You should run this:
USE master
EXEC sys.sp_MS_marksystemobject 'dbo.sp_your_proc_name_here'

The point of creating it in master...

I recommend you create a procedure in the master db that can automatically run in the context of any db you need.  Below is the code to create the proc....

ROW_NUMBER() is not gonna work prior to SQL 2005 either anyway :-).