Use columns from select statement as parameter in function when joining [duplicate]

Question

This question already has an answer here:

pass parameter in table valued function using select statement (1 answer)

Closed 6 years ago.

Consider the following sql query:

SELECT TaskId,FromItemId, IHV_FROM.NodePath as FromPath
FROM VIEW_TASKS with (nolock) 
left Join fn_ITEM_HIERARCHY(FromItemId) IHV_FROM ON FromItemId = IHV_FROM.ItemId
WHERE ...

fn_ITEM_HIERARCHY is a function which takes one input parameter. I would like to use FromItemId from VIEW_TASKS as input parameter to the function. When doing it like above, i get the error (Microsoft SQL Server 2008) "Invalid column name".

The SELECT statement returns multiple values, so it is not possible to assign the value to a variable in a separate select statement. Any ideas?

Answer 1

You probably need to use OUTER APPLY in this case:

SELECT TaskId,FromItemId, IHV_FROM.NodePath as FromPath
FROM VIEW_TASKS with (nolock) 
OUTER APPLY fn_ITEM_HIERARCHY(FromItemId) IHV_FROM
WHERE ...
;

If the function always returns rows or if you only want results for values where the function does return rows, use CROSS APPLY instead.

Answer 2

Use Cross apply as shown here

http://blog.sqlauthority.com/2008/01/03/sql-server-2005-last-ran-query-recently-ran-query/

Answer 3

use alias

SELECT t.TaskId, t.FromItemId, IHV_FROM.NodePath as FromPath
FROM VIEW_TASKS t with (nolock) 
left Join fn_ITEM_HIERARCHY(FromItemId) IHV_FROM ON t.FromItemId = IHV_FROM.ItemId

Answer 4

use OUTER APPLY instead of left join