Multiple Part Identifier could not be bound in a Derived Table - sql

Question

I'm trying to run the SUM of MAX values, and then updating them into a column. I think the derived table is the right way to go, but now I keep getting a multi-part id could not be bound error that I dont know how to get round.
I'm running this on SSMS, and it will be my Db for a PowerApp. I'm essentially trying to take the distinct or MAX values of Assessment Hours from multiple Units, then add those together, grouped by the Staff ID number. I'm working with a derived table to try and mix the two aggregate functions.
WITH pretotalAssessment as
(
SELECT dbo.StaffTotals.Entry_ID, ISNULL(SUM(maxAssess),0) AS maxAssessHours
FROM
(
SELECT dbo.StaffTotals.Entry_ID, dbo.Units.[Unit Name],
ISNULL(MAX(dbo.Units.[Assessment Hours]),0) AS maxAssess
FROM dbo.Units
INNER JOIN dbo.StaffTotals ON dbo.StaffTotals.Entry_ID = dbo.Units.Entry_ID
GROUP BY dbo.StaffTotals.Entry_ID,dbo.Units.[Unit Name]
)Units
)
UPDATE preStaffTotals
SET preStaffTotals.Assessment = pretotalAssessment.maxAssessHours
FROM dbo.StaffTotals AS preStaffTotals
INNER JOIN pretotalAssessment ON preStaffTotals.Entry_ID = pretotalAssessment.Entry_ID;
My error is:
"The multi-part identifier "dbo.StaffTotals.Entry_ID" could not be bound."
I'm still quite new to SQL, so this is all a learning curve for me!

Answer 1

Your first SELECT in the CTE is from a derived table. That means that dbo.StaffTotals isn't accessible in the SELECT list.
You need to replace:
SELECT dbo.StaffTotals.Entry_ID
With:
SELECT Units.Entry_ID

Answer 2

You are SELECTING the full [schema].[tableName].[columnName] of dbo.StaffTotals.Entry_ID FROM Units.
Change to the below and it should work;
WITH pretotalAssessment as
(
SELECT Entry_ID, ISNULL(SUM(maxAssess),0) AS maxAssessHours
FROM
(
SELECT dbo.StaffTotals.Entry_ID, dbo.Units.[Unit Name],
ISNULL(MAX(dbo.Units.[Assessment Hours]),0) AS maxAssess
FROM dbo.Units
INNER JOIN dbo.StaffTotals ON dbo.StaffTotals.Entry_ID = dbo.Units.Entry_ID
GROUP BY dbo.StaffTotals.Entry_ID,dbo.Units.[Unit Name]
)Units
GROUP BY Entry_ID
)
UPDATE preStaffTotals
SET preStaffTotals.Assessment = pretotalAssessment.maxAssessHours
FROM dbo.StaffTotals AS preStaffTotals
INNER JOIN pretotalAssessment ON preStaffTotals.Entry_ID = pretotalAssessment.Entry_ID;
I would also suggest using COALESCE() instead of ISNULL() as COALESCE() is the ANSI standard and ISNULL() isn't. Also COALESCE() can have multiple arguments, whereas ISNULL() can only have 1. So easier for future dev changes. so;
WITH pretotalAssessment as
(
SELECT Entry_ID, COALESCE(SUM(maxAssess),0) AS maxAssessHours
FROM
(
SELECT dbo.StaffTotals.Entry_ID, dbo.Units.[Unit Name],
COALESCE(MAX(dbo.Units.[Assessment Hours]),0) AS maxAssess
FROM dbo.Units
INNER JOIN dbo.StaffTotals ON dbo.StaffTotals.Entry_ID = dbo.Units.Entry_ID
GROUP BY dbo.StaffTotals.Entry_ID,dbo.Units.[Unit Name]
)Units
GROUP BY Entry_ID
)
UPDATE preStaffTotals
SET preStaffTotals.Assessment = pretotalAssessment.maxAssessHours
FROM dbo.StaffTotals AS preStaffTotals
INNER JOIN pretotalAssessment ON preStaffTotals.Entry_ID = pretotalAssessment.Entry_ID;