Call function for every row of a table without cross apply - tsql

Question

I have this tsql function which inserts into a table variable:
create function fnListInfo(#id int) returns #res table(
[itemId] INT,
[name] NVARCHAR(255),
[type] NVARCHAR(20),
[unit] INT,
[order] INT
)
BEGIN
INSERT INTO #res
SELECT category.stockcat_id, category.stockcat_name, category.type, NULL /*unit*/, category.order
FROM tblStock stock
JOIN dbo.Map category on stock.id = category.itemId
WHERE stock.id = #id
insert into #res
SELECT t.*
FROM #res r
CROSS APPLY dbo.anotherFunction(r.itemId) AS t
WHERE r.type = 'parent'
RETURN
END
GO
In the end of fnListInfo, I want to add some more rows to the res table. If the row in #res is of type 'parent', I want to call another function (let's call it anotherFunction) which has the same return type as this one, and its input parameter is int (itemId from fnListInfo), and then I want to add the result from anotherFunction to #res in fnListInfo.
So basically I want to call anotherFunction for every row in #res which is of type 'parent' and append the result to the already existing #res.
I tried doing this:
insert into #res
SELECT t.*
FROM #res r
CROSS APPLY dbo.anotherFunction(r.itemId) AS t
WHERE r.type = 'parent'
and it works. The problem is that it's inefficient. Is there a better way?
I don't like using cursors.

Answer 1

Try changing your function to inline table valued function:
CREATE FUNCTION dbo.fnListInfo(#id int)
RETURNS TABLE
AS
RETURN (
SELECT t.*
FROM (
SELECT category.stockcat_id AS ItemId, category.stockcat_name AS name,
category.type AS [type], NULL AS [unit] , category.[order] AS [order]
FROM tblStock stock
JOIN dbo.Map category
ON stock.id = category.itemId
WHERE stock.id = #id) AS r
CROSS APPLY dbo.anotherFunction(r.itemId) AS t
WHERE r.type = 'parent'
UNION ALL
SELECT category.stockcat_id AS ItemId, category.stockcat_name AS name,
category.type AS [type], NULL AS [unit] , category.[order] AS [order]
FROM tblStock stock
JOIN dbo.Map category
ON stock.id = category.itemId
WHERE stock.id = #id
);
You should change dbo.anotherFunction to inline table valued function too if possible.
I suggest also reading about Inline vs Multistatement Table Function