有什么办法可以提高效率吗？它运行速度快，只是希望改进（如果有的话）
有什么办法可以提高效率吗？
internal Func<enntities, IQueryable<CategoryList>> GetCategoryListWithPostingCount =
CompiledQuery.Compile((entities entities) =>
from c in entities.Categories.Include("Postings_Categories")
where c.ParentCategoryID == null
orderby c.DisplayOrder
select new CategoryList
{
ParentCategoryName = c.CategoryName,
ParentCategoryID = c.CategoryID,
SubCategories = (
from s in entities.Categories
where s.ParentCategoryID == c.CategoryID
select new SubCategoryList
{
PostingCount = s.Postings_Categories.Count,
SubCategoryName = s.CategoryName,
SubCategoryID = s.CategoryID
})
});
Any way to make this more efficient?
internal Func<enntities, IQueryable<CategoryList>> GetCategoryListWithPostingCount =
CompiledQuery.Compile((entities entities) =>
from c in entities.Categories.Include("Postings_Categories")
where c.ParentCategoryID == null
orderby c.DisplayOrder
select new CategoryList
{
ParentCategoryName = c.CategoryName,
ParentCategoryID = c.CategoryID,
SubCategories = (
from s in entities.Categories
where s.ParentCategoryID == c.CategoryID
select new SubCategoryList
{
PostingCount = s.Postings_Categories.Count,
SubCategoryName = s.CategoryName,
SubCategoryID = s.CategoryID
})
});
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评论（1）
任何改进建议都取决于我们了解的不仅仅是 LINQ 查询。例如，如果每个类别有很多子类别列表，并且类别附加有很多标量数据（大描述文本等），则在单独的数据库往返中提取类别列表可能会更快。但可能不会。
查看连接了哪些表并添加适当的索引也可能会有所不同。
但总而言之，我想说这是一个过早优化的情况。代码看起来很干净，我可以告诉你你想用它做什么，所以现在就说这很好。如果您发现这是程序中的一个慢点，请担心它。
PS--这个问题被标记为 LINQ-to-SQL，但这对我来说看起来像 LINQ-to-Entities...
Any suggestions for improvement would depend on us knowing a lot more than just the LINQ query. For example, if you have a lot of SubCategoryLists per Category, and if Category has a lot of scalar data attached to it (big description text, etc), it might be faster to pull the category list in a separate database round-trip. But it probably won't.
Looking at what tables are joined and adding the appropriate indices could make a difference, too.
But all in all, I'd say this is a case of premature optimization. The code looks clean, and I can tell what you're trying to do with it, so call that good for now. If you find that it's a slow point in your program, worry about it then.
PS--The question is tagged LINQ-to-SQL, but this looks like LINQ-to-Entities to me...