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Remove need for second T-SQL query

I am loading some data into a repeater which is coming from two tables. The query against the second table is only selecting the MAX record though, and because of this complexity, I'm having to create a child repeater to then go off and find the Max record to display.
Table A: Activity List
ID | Activity
----+-----------------------
1 | Change Oil Filter
2 | Change brake fluid
3 | Change brake rotors
Table B: Mechanics Log
ID | ActivityID | Date | Mechanic | Comment
---+-------------+-------------+-------------------------------------------
1 | 1 | 2019-27-06 | John | Changed the oil filter
2 | 1 | 2019-26-06 | Sally | No oil filters in stock.
3 | 2 | 2019-20-06 | Sally | Brake fluid flushed.
As stated above, I can produce the following table using two repeaters (one inside the other) and it looks like this.
ActivityID | Date | Mechanic | Comment
-------------+-------------+-----------------------------------------
1 | 2019-27-06 | John | Changed the oil filter
2 | 2019-20-06 | Sally | Brake fluid flushed.
3 | | |
My question is: How can I produce the same table but using only one repeater and 1 T-SQL query? Is it possible? The reason being is that this is a very simple list (shortened for this demonstration) of the full list I have to enable for my mechanics work log, and when i start going to 100+ activities that can be done on a vehicle, the page loads quite slow; assuming because it has to fire off the 2nd repeater + code for each record it has bound.
I also apologize I do not yet have a 'starting point' for you to work with, as nothing I have created has come even close to producing the result in one query. I am having trouble working out how I combine the first part of the query with the MAX(Date) of the 2nd table. Hoping for some assistance from the community to help.

You can use the below query to get the desired result -
Sample Data
Declare #ActivityList Table
(ID int, Activity varchar(100))
Insert into #ActivityList
values
(1 , 'Change Oil Filter' ),
(2 , 'Change brake fluid' ),
(3 , 'Change brake rotors' )
Declare #MechanicsLog Table
(ID int, ActivityID int, [Date] Date, Mechanic varchar(20), Comment varchar(50))
Insert into #MechanicsLog
values
(1 , 1 , '2019-06-27' , 'John' , 'Changed the oil filter' ),
(2 , 1 , '2019-06-26' , 'Sally' , 'No oil filters in stock.' ),
(3 , 2 , '2019-06-20' , 'Sally' , 'Brake fluid flushed.' )
Query
;With cte as
(select ActivityID, Max([Date]) [date] from #MechanicsLog ml
Group By ActivityID
)
Select al.ID, al.Activity, cte.[Date], Mechanic, Comment
from cte inner join #MechanicsLog ml
on cte.ActivityID = ml.ActivityID and cte.[date] = ml.[Date]
right join #ActivityList al on al.ID = ml.ActivityID
order by ID

If you add use the ROW_NUMBER function to add a sequence to each activity ID, you can then filter that to only get the most recent for each activity ID.
select ActivityID, Date, Mechanic, Comment
from
(
select *, ROW_NUMBER() OVER (PARTITION BY ActivityID order by Date desc) RowNumber
from MechanicsLog
) q1
where RowNumber = 1
This gives you the "MAX" record for each ActivityID but with the rest of the record, so you can join to the Activity List table if you want.

select
act.ActivityID, Max(log.[Date]) as [Date]
from
ActivityList act
inner join
MachineLog log on log.ActivityID = act.ActivityID
Group by
act.ActivityID

how to show remaining data by comparing another table

Table 1: ABC table 2: PQR
code|Name|Amount code|Name|Amount
----+----+----- ----+----+------
1 | A | 1000 1 | A | 1000
2 | B | 2000 2 | B | 2000
3 | C | 4000
4 | D | 1000
data in table 2 is insert from data based on table 1, now by pressing a button named "Remaining" i want to show data that is not present in table 2, to know which tuples i have missed to fill from table 1. How can i do it?

If the fields in the 2 tables are exactly the same and in the same order?
But you can't bother to put those fields in the SQL?
Then you could also use an EXCEPT
SELECT * FROM ABC
EXCEPT
SELECT * FROM PQR;
And if you're not certain that the fields are in the same order?
Then list them in the SQL.
That has also the benefit that the SQL will probably still work when one of the tables is altered.
SELECT [code], [Name], [Amount] from ABC
EXCEPT
SELECT [code], [Name], [Amount] FROM PQR;
It filters out the PQR records that are exactly the same as those found in ABC.
But normally, the methods that Tim Biegeleisen showed are more commonly used.

This answer assumes that you want to find all records in the first table which are not already present in the second table. One option uses a left join:
SELECT t1.*
FROM ABC t1
LEFT JOIN PQR t2
ON t1.code = t2.code AND t1.Name = t2.Name AND t1.Amount = t2.Amount
WHERE t2.code IS NULL;
We could also phrase this using EXISTS:
SELECT t1.*
FROM ABC t1
WHERE NOT EXISTS (SELECT 1 FROM PQR t2
WHERE t1.code = t2.code AND t1.Name = t2.Name AND
t1.Amount = t2.Amount);

Update table column based on comparison of columns from 2 table (SQL)

I have the following tables.
Table 1
Id | Values | Counts
1 | rock | 0
2 | tina | 0
3 | alex | 0
Table 2
Id | Values
1 | rock
2 | alex
3 | alex
4 | rock
5 | rock
6 | tina
As you can see, table 1 contains Values as rock, tina and alex. These column will always have unique values. Counts column should check the count of 'rock' in Table 2 and update it in Counts column. for e.g. rock is shown 3 times in table 2. The counts for rock should be then 3.
Similarly for other values. Can someone pls let me know how can i achieve this using SQL. Here is how the final table should look like.
Table 1
Id | Values | Counts
1 | rock | 3
2 | tina | 1
3 | alex | 2
Any help is appreciated. I searched online and couldnot find a possible solution for this scenario.

You can generally use a JOIN between 2 tables to update Table1 with values from Table2 (or further if you are using bridge tables).
UPDATE t1
SET t1.dataColumn = t2.dataColumn
FROM Table1 t1
INNER JOIN Table2 t2 ON t1.keyColumn = t2.keyColumn
However, when you are using Aggregate functions (such as Count, Sum)you must utilize a subquery for the second table and perform the JOIN to that subquery
UPDATE t1
SET t1.Counts = sb.Counts
FROM Table1 AS t1
INNER JOIN (
SELECT [values], Counts = Count([values])
FROM Table2
GROUP BY [values]
) AS sb
ON t1.[values] = sb.[values]
Running this on your tables gave me this:
SELECT * FROM Table1
id values counts
---- ------- -------
1 rock 3
2 tina 1
3 alex 2
One thing concerning your table design; I generally recommend not using reserved/special/key words when naming tables, columns, or other database objects. I also try to avoid using the generic name id because it can get confusing when you start linking tables to one another, even idTable1 can make things a lot easier

In SQL Server, using a correlated subquery:
update t1
set t1.Counts = (
select count(*)
from t2
where t2.[Values] = t1.[Values]
);
rextester demo: http://rextester.com/SBYNB72372
In MySQL, using a correlated subquery:
update t1
set t1.Counts = (
select count(*)
from t2
where t2.`Values` = t1.`Values`
);
rextester demo: http://rextester.com/DDDC21719
Although this sort of thing might be better calculated in a view instead of stored in the t1 table.
In SQL Server:
create view dbo.t1_with_counts as
select t1.Id, t1.[Values], count(t2.[Values]) as Counts
from t1
left join t2
on t1.[Values] = t2.[Values]
group by t1.Id, t1.[Values]
go
select *
from dbo.t1_with_counts;
In MySQL:
create view t1_with_counts as
select t1.Id, t1.`Values`, count(t2.`Values`) as Counts
from t1
left join t2
on t1.`Values` = t2.`Values`
group by t1.Id, t1.`Values`;
select *
from t1_with_counts;

I would question the wisdom of keeping track of a count in a table like that. That leads to poor relational database structure and management. Instead, I suggest you remove the count column from Table 1. Then, whenever you need to see the counts you use a view:
SELECT t1.ID, t1.VALUES, COUNT(t2.ID) AS VALUE_COUNT
FROM TABLE1 t1 LEFT JOIN TABLE2 t2 ON t1.VALUES = t2.VALUES
This results in a dynamically updated view of your data instead of a static view that has the potential for going stale without your realizing it.

Stored Procedure for date ranges in a single column

Finding a solution to an issue in my project
I have stages associated with contracts. That is, a contract can be in either Active stage, Process stage or Terminated stage.
I need to get the no the days the contract was in each stage.
For example, if a contract C1 was in Active stage from 20/10/2013 to 22/10/2013, then in the Process stage from 22/10/2013 to 25/10/2013 and finally in Terminated stage from 25/10/2013 to 26/10/2013 and then again in Active from 26/10/2013 to 28/10/2013, then I should get as result
Active = 4days
Process = 3days
Terminated = 1day /likewise something
My table is created with these columns:
EntryId (primary key)
StageId (foreign key to Stage table)
ContractId (foreign key to contract table)
DateofStageChange
How to do this in SQL Server?
As asked pls find the table entries:
EntryID | Stage ID | Contract ID | DateChange
1 | A1 | C1 |20/10/2013
2 | P1 | C1 |22/10/2013
3 | T1 | C1 |25/10/2013
4 | A1 | C1 |26/10/2013
5 | P1 | C1 |28/10/2013
6 | T1 | C1 |Null(currently in this stage)
Need to use group by on Stage ID

it is important to check and make sure how data is populated in your table.Based on just your sample data and also note that if your entryid is not in sequence then you can create one sequence using row_number.
declare #t table(EntryId int identity(1,1), StageId int,ContractId varchar(10),DateofStageChange date)
insert into #t values
(1,'C1','2013-10-20'),(1,'C1','2013-10-22'),(2,'C1','2013-10-22'),(2,'C1','2013-10-25')
,(3,'C1','2013-10-25'),(3,'C1','2013-10-26'),(1,'C1','2013-10-26'),(1,'C1','2013-10-28')
Select StageId,sum([noOfDays]) [totalNofDays] from
(select a.StageId,a.ContractId,a.DateofStageChange [Fromdate],b.DateofStageChange [ToDate]
,datediff(day,a.DateofStageChange,b.DateofStageChange) [noOfDays]
from #t a
inner join #t b on a.StageId=b.StageId and b.EntryId-a.EntryId=1)t4
group by StageId

You can't with your current structure.
You can get the latest one by doing datediff(d, getdate(), DateOfStageChange)
but you don't have any history so you can't get previous status

This can be done in SQL with CTE.
You didnt provide your tablenames, so you'll need to change where I've indicated below, but it would look like this:
;WITH cte
AS (
SELECT
DateofStageChange, StageID, ContractID,
ROW_NUMBER() OVER (ORDER BY ContractID, StageId, DateofStageChange) AS RowNum
FROM
DateOfStageChangeTable //<==== Change this table name
)
SELECT
a.ContractId,
a.StageId,
Coalesce(sum(DATEDIFF(d ,b.DateofStageChange,a.DateofStageChange)), 'CurrentState`) as Days
FROM
cte AS A
LEFT OUTER JOIN
cte AS B
ON A.RowNum = B.RowNum + 1 and a.StageId = b.StageId and a.ContractId = b.ContractId
group by a.StageId, a.ContractId
This really is just a self join that creates a row number on a table, orders the table by StageID and date and then joins to itself. The first date on the first row of the stage id and date, joins to the second date on the second row, then the daterange is calculated in days.
This assumes that you only have 2 dates for each stage, if you have several, you would just need to do a min and max on the cte table.
EDIT:
Based on your sample data, the above query should work well. Let me know if you get any syntax errors and I'll fix them.
I added a coalesce to indicate the state they are currently in.

Gnarly Linq query

Have the following table structure
I need the count of transcriptions by statuses where the records do not have a workflow folder. This does the trick:
from p in Transcriptions
where p.WorkflowfolderID == null
group p by p.TranscriptionStatus.Description into grouped
select new
{
xp=grouped.Key,
xp1= grouped.Count(),
}
Now I need to add the number of records where the Dueon date is in the past as in it is past the due by date.Something like
EntityFunctions.DiffHours(p.DueOn,DateTime.Today)>0
How do I include this in the resultset without firing 2 SQL queries? I am happy to get it as a third column with the same value in every row. Also is there anyway to get the percentage into the mix as in:
Status | Count | % |
------------------------------
Status1 | 20 | 20%
Status2 | 30 | 30%
Status3 | 30 | 30%
Overdue |20 | 20%
I have added Overdue as a row but perfectly happy to get it as a column with the same values.
Edited Content
Well this is the best I could come up with. Its not a single query but there is only one SQL trip. The result is:
Status | Count
----------------
Status1 | 20
Status2 | 30
Status3 | 30
Overdue |20
var q1= from p in Transcriptions
where p.WorkflowfolderID == null
group p by p.TranscriptionStatus.Description into grouped
select new
{
status= (string)grouped.Key,
count= grouped.Count()
};
var q2 =(
from p in Transcriptions select new {status = "Overdue",
count = (from x in Transcriptions
where x.DueOn.Value < DateTime.Now.AddHours(-24)
group x by x.TranscriptionID into
grouped select 1).Count() }).Distinct();
q1.Union(q2)
It is a Union clause with the % calculation to be done once the results are returned. The weird thing is that I couldn't figure out any clean way to represent the following SQL in a LINQ statement which has resulted in the rather messy LINQ in the var q2.
SELECT COUNT(*) , 'test' FROM [Transcription]

You can add a condition to Count:
from p in Transcriptions
where p.WorkflowfolderID == null
group p by p.TranscriptionStatus.Description into grouped
select new
{
xp=grouped.Key,
xp1= grouped.Count(),
xp2= grouped
.Count(p => EntityFunctions.DiffHours(p.DueOn, DateTime.Today) > 0)
}
By the way, with entity framework you can also use p.DueOn < DateTime.Today.

#Gert Arnold
from p in Transcriptions
where p.WorkflowfolderID == null
group p by p.TranscriptionStatus.Description into grouped
select new
{
status= (string)grouped.Key,
count= grouped.Count(),
overdue= grouped.Count(p => p.DueOn < EntityFunctions.AddHours(DateTime.Today, -24)),
}
The above query does work as I wanted it to . It produces the outcome in the format
Status| Count | Overdue
----------------------
status1|2|0
status2|1|1
The only downside is the generated SQL is running 2 queries BOTH with inner joins . My original idea with the Union may be a better idea performance wise but you answered my query and for that I am grateful.
Can this query be represented in some other cleaner manner than my above attempt -
SELECT COUNT(*) , 'test' FROM [Transcription]