Update table with date conversion failing on Multi-Part Identifier - sql

Question

Thanks to the guys with suggestions on date conversion yesterday, I now have a working SELECT script.
Unfortunately, when I try to turn it into an UPDATE script, I get the dreaded
Msg 4104, Level 16, State 1, Line 25
The multi-part identifier "mbrProject.ID" could not be bound.
The entire script should insert the date from mbrProject into ProjectDates, for each matching ID (mbrProject.[ID] = ProjectDates.[Project_ID]), whilst resolving mixed US & UK format dates in mbrProject, due to users having incorrect country settings when updating the tables (not changeable from my end).
Update ProjectDates
SET ProjectDates.[Start_Date] =
(
select right([Start_Date],4) +
case
when len([Start_Date])=10 then
substring([Start_Date],4,2) + left([Start_Date],2)
else right('0' + left([Start_Date],firstIndex-1),2) +
right('0' + substring([Start_Date],firstIndex+1,secondIndex - firstIndex-1),2)
end
from
(
select mp.[Start_Date], charindex('/',mp.[Start_Date],1) firstIndex,
charindex('/',mp.[Start_Date],charindex('/',mp.[Start_Date],1)+1) secondIndex
from mbrProject mp
join ProjectDates pd
on mp.ID = pd.Project_ID
)A
where mbrProject.[ID] = ProjectDates.Project_ID
)
If I run ONLY the SELECT statement, it works fine, returning the correct values.
i.e Everything from
select right([Start_Date],4) +
case
down to
from mbrProject mp
join ProjectDates pd
on mp.ID = pd.Project_ID
)A
However, as soon as I try to wrap it up in the UPDATE statement, I get the error.
I know that this is down to syntax, but wherever I try to move stuff, I can't quite figure it out.
Any ideas please?
Thanks
Craig

Answer 1

Try this:
UPDATE PR
SET PR.[Start_Date] = A.[Corrected_Start_Date]
FROM ProjectDates PR
JOIN
(
SELECT
[Id],
RIGHT([Start_Date],4) +
CASE
WHEN len([Start_Date])=10
THEN substring([Start_Date],4,2) + LEFT([Start_Date],2)
ELSE RIGHT('0' + LEFT([Start_Date],firstIndex-1),2) +
RIGHT('0' + substring([Start_Date],firstIndex+1,secondIndex - firstIndex-1),2)
END [Corrected_Start_Date]
FROM
(
SELECT
[Id],
[Start_Date],
charindex('/',[Start_Date],1) firstIndex,
charindex('/',[Start_Date],charindex('/',[Start_Date],1)+1) secondIndex
FROM mbrProject
) S
) A
ON A.[ID] = PR.[Project_ID]

Answer 2

(
select mp.[Start_Date], charindex('/',mp.[Start_Date],1) firstIndex,
charindex('/',mp.[Start_Date],charindex('/',mp.[Start_Date],1)+1) secondIndex
from mbrProject mp
join ProjectDates pd
on mp.ID = pd.Project_ID
)A
At the end of the last line here, the names mp, pd, mbrProject and (the inner ProjectDates) no longer exist as table names or aliases. The only name applicable to this row set from here on is A, the alias you've provided.
So you need to include mp.ID in your select list, and then use A.ID in your outer comparison.
Also, not knowing what you're trying to do, I'd just want to make sure you're aware that ProductDates (the table being updated) and pd are referring to two separate instances of that table, an inner one and an outer one. I'm hoping that the final WHERE should be:
where A.[ID] = ProjectDates.Project_ID

Answer 3

The problem is that doing
Update ProjectDates
SET ProjectDates.[Start_Date] = (select ...)
you are trying to set one field of one row to the results of the sub-select statement, which, I presume, is returning multiple values.