JOIN technique

Create Procedure dbo.sp_JoinTechnique

@BrandId_List varchar = ''-- for all brands the list would be empty

AS 
BEGIN
/* Execution sample
exec dbo.sp_JoinTechnique ',2,3,5,6,' 

*/
-- Using the function developed by my friend, CVMichael, and me,  the dbo.fn_SplitStringToTable
	DECLARE @tbl_Brands TABLE (BrandID INT)
		
		INSERT INTO @tbl_Brands
		SELECT ItemData 
		FROM dbo.fn_SplitStringToTable (ISNULL(@BrandId_List,''),',') your_Brands

	--I can do it like this:

	SELECT *
	FROM 
		Sales s
			INNER JOIN	Products p on c.customerId = p.customerId
			INNER JOIN	Brands b on p.BrandId = b.BrandId -- do the LEFT JOIN Brands if you have products without brands
			LEFT JOIN	@tbl_Brands tb on b.brandId = tb.BrandId
	WHERE
		@BrandId_List = '' 
		OR 
		tb.BrandId is NOT NULL
		
	--OR I can do it like this (the way I RECOMMEND):
	
	SELECT *
	FROM 
		Sales s
			INNER JOIN	Products p on c.customerId = p.customerId
			LEFT JOIN	Brands b 
				INNER JOIN	@tbl_Brands tb on b.brandId = tb.BrandId
			on p.BrandId = b.BrandId
	WHERE
		@BrandId_List = '' 
		OR 
		b.BrandId is NOT NULL
		
	--You can use this technique instead of:
/*
	...	INNER JOIN	Products p on c.customerId = p.customerId
			LEFT JOIN (SELECT br.* FROM Brands br INNER JOIN	@tbl_Brands tb on br.brandId = tb.BrandId) b
		on p.BrandId = b.BrandId
*/	
END