Tables :CREATE TABLE [Production].[Products]( [productid] [int] IDENTITY(1,1) NOT NULL, [productname] [nvarchar](40) NOT NULL, [supplierid] [int] NOT NULL, [categoryid] [int] NOT NULL, [unitprice] [money] NOT NULL, [discontinued] [bit] NOT NULL, CONSTRAINT [PK_Products] PRIMARY KEY CLUSTERED ( [productid] ASC)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]) ON [PRIMARY]GOCREATE TABLE [Production].[Categories]( [categoryid] [int] IDENTITY(1,1) NOT NULL, [categoryname] [nvarchar](15) NOT NULL, [description] [nvarchar](200) NOT NULL, CONSTRAINT [PK_Categories] PRIMARY KEY CLUSTERED ( [categoryid] ASC)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]) ON [PRIMARY]GOI wrote this code using cross apply :select c.categoryid,a.productid,a.productname, a.unitpricefrom Production.Categories as ccross apply ( select productid, productname, unitprice from Production.Products as p where c.categoryid=p.categoryid order by categoryid, unitprice offset 0 rows fetch first 1 rows only) as aorder by categoryidgo My book suggested CTE like this :with CTE_min as ( select categoryid, min(unitprice) as mn from Production.Products group by categoryid)select p.categoryid, p.productid, p.productname, p.unitpricefrom Production.Products as pJOIN CTE_min as m on p.categoryid=m.categoryidand p.unitprice=m.mn ;This database is TSQL2012, I am learning for SQL Server MCSA. Exercise was to write a solution that uses a CTE to return the products with the lowest unit price per category. I done it but later I write this cross apply solution as well, i run Actual Execution plan and it was 88% for cross join and only 12% for CTE. My question is why is CTE so much better?English isn't my native, thanks in advance.
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