No, database and/or log backups would not cause this error.

SELECT VendorName
FROM VenInfo
GROUP BY VendorName
HAVING SUM(CASE WHEN VenSN = 'Y' THEN 1 ELSE 0 END) * 100.0 / SUM(1) >= 80

Nor trying to be difficult, but that just lists the values, it doesn't assign them as the table ID in the existing table, as stated in the OP.

You could schedule a job to run on the first of the month, but immediately exit the job if that day is a Sunday.  Add a second sched to that...

To be absolutely clear, you want a:

2) unique clustered [index] on (tenant,year,id)

And if you partition the data (which typically wouldn't be necessary here), partition it by...

You can, and definitely should, get rid of the other ISNULLs in your WHERE:

AND ISNULL(d.value_2,'') NOT IN ('Clay','Volusia') --replace with -->  AND d.value_2 NOT IN ('Clay','Volusia')

AND ISNULL(rc.referral_category_ud,'') <>...

You can, and definitely should, get rid of the other ISNULLs in your WHERE:

AND ISNULL(d.value_2,'') NOT IN ('Clay','Volusia') --replace with

-->  AND d.value_2 NOT IN ('Clay','Volusia')

AND ISNULL(rc.referral_category_ud,'') <> 'FFS_NO_TAKE_BAC' --replace with

-->...

To be absolutely clear, you want a:

2) unique clustered [index] on (tenant,year,id)

And if you partition the data (which typically wouldn't be necessary here), partition it by (tenant, year)...

It is.  Google for function "dbo.DelimitedSplit8K".  It's a function you install once and can use from then on for this.

To be absolutely clear, you want a:

2) unique clustered [index] on (tenant,year,id)

And if you partition the data (which typically wouldn't be necessary here), partition it by (tenant, year) not just...

Seems like you might be looking for a total?!:

SELECT yt.account_number, SUM(ca1.Debit) AS Total_Debits, SUM(ca1.Credit) AS Total_Credits, 
    SUM(ca1.Debit) - SUM(ca1.Credit) AS Net_Amount
FROM dbo.your_table yt
CROSS...

Use COALESCE instead:

COALESCE(fa.S1SDAT, ar2.S1ADAT, ar.S1SDATE)

...

Definitely use char(2) for the values, as suggested (varchar requires two bytes of extra overhead (to store length) per column).

If they're not already encoded, encode the names.  That is, "Code1"...

Yes, those procs will both run under the same transaction (assuming no COMMIT(s) in the procs).

? Don't see anything attached ?