Not much to go on, but, in general, just put the appropriate conditions in the WHERE clause:

DECLARE @key_value ...
DECLARE @col_value ...

SET @key_value = ...
SET @col_value = ...

UPDATE...

Keep in mind, too, that the point of naming is to give accurate business names to objects, not to make things easier for developers.  That is, just because a naming...

With stored procedures, I like a 2-3 letter acronym at the start to define the process (adm for admin, fin for finance, etc) followed by _ and then what...

Give your databases names that reflect their business purpose.  Don't use prefixes or suffixes in the name to indicate "database".  MS got this half right: MS has dbs "master", "model",...

Make sure the D_Date table is uniquely clustered on Date (it should already be, but verify, just in case).  I'd stick with a scalar function for now, but get rid...

Actually, for an even number of rows, the median is the avg of the middle two (IIRC).

For example, for values:

1, 2, 3, 101, 200, 500 :: median is 52 (...

Agreed, we need to see the code.

And, do you have a table with non-workdays in it?  We'll need to know the DDL for that table to properly determine business days.

That's not an accurate method to get a median value.

For example, if you have these values:

SELECT (MAX(value) - MIN(value)) / 2 + MIN(value)

FROM ( VALUES(1),(2),(3),(1000),(3000) ) AS data(value)

the median (middle) value...

;WITH cte_add_row_nums AS (
    SELECT *, ROW_NUMBER() OVER(PARTITION BY Id ORDER BY Branch) AS row_num
    FROM #temp
)
SELECT id, branch, city
FROM cte_add_row_nums
WHERE...

You might be able to use a login trigger to deny the connection for those specific users if they were not coming from a linked server.  You'd have to review...

NTILE specifies the number of groups, not the size of each group.  So in your example it should be 100 not 800.

For the sample data shown, 10 groups makes more...

I agree with Phil.  I would use a "holding" table to contain the data prior to it being summarized in 15-minute "packets" to be added to the main table.

Scott, fyi...I do have a clustered index defined for the column that is the primary key - an IDENTITY column.

[UserId] [int] IDENTITY(1,1) NOT NULL,

CONSTRAINT [PK_User] PRIMARY KEY CLUSTERED (...

I

[1] To log in, I request a User Name. Should I have a non-clustered index on that column?

[2] Also, in another table, I query on the email address, should...

Maybe something like this?:

ALTER TABLE dbo.your_table_name ADD REPORT_DATE AS CAST(DATEADD(DAY, CASE WHEN CREATE_TIME >= '18:00:00' THEN 1 ELSE 0 END, CREATE_DATE) AS date) PERSISTED;

...

WHERE REPORT_DATE = CAST(GETDATE() AS date)