.Net 性能优化--EFCore(EntityFrameworkCore)--懒加载和数据上下文dbcontext添加数据
新建.NET CORE CONSOLE控制台项目NetCoreConsole，管理NuGet程序包种添加一下引用
//Microsoft.EntityFrameworkCore //EFCore
//Microsoft.Extensions.Logging // 日志
//Microsoft.Extensions.Logging.Console // 日志输出到Console控制台
//Microsoft.Extensions.Logging.Debug // 日志输出到调试Debug
//Microsoft.EntityFrameworkCore.Proxies// 懒加载，延迟加载，EFCore没有懒加载，使用该库，可以实现懒加载
//Microsoft.EntityFrameworkCore.SqlServer//EFCore使用的SqlServer数据库
//Pomelo.EntityFrameworkCore.MySql//EFCore使用的MySql数据库
项目代码如下：
using Microsoft.EntityFrameworkCore; using System; using System.Collections.Generic; using Microsoft.Extensions.Logging; using System.Linq; using System.Diagnostics; using Microsoft.EntityFrameworkCore.Storage; //Microsoft.EntityFrameworkCore //EFCore //Microsoft.Extensions.Logging // 日志 //Microsoft.Extensions.Logging.Console // 日志输出到Console控制台 //Microsoft.Extensions.Logging.Debug // 日志输出到调试Debug //Microsoft.EntityFrameworkCore.Proxies// 懒加载，延迟加载，EFCore没有懒加载，使用该库，可以实现懒加载 //Microsoft.EntityFrameworkCore.SqlServer//EFCore使用的SqlServer数据库 //Pomelo.EntityFrameworkCore.MySql//EFCore使用的MySql数据库 namespace NetCoreConsole { class Program { static void Main(string[] args) { Console.WriteLine("测试 EF core "); BlogContext blogContext = new BlogContext(); #region ef 数据库的创建和删除 //Console.WriteLine("删除数据库"); //blogContext.Database.EnsureDeleted(); //Console.WriteLine("添加数据库"); blogContext.Database.EnsureCreated(); //Console.WriteLine("添加数据库成功"); #endregion #region 数据迁移相关 //IEnumerable<string> vs = blogContext.Database.GetMigrations(); //blogContext.Database.GetPendingMigrations(); //blogContext.Database.GetAppliedMigrations(); //blogContext.Database.Migrate(); //Console.WriteLine("添加数据库成功"); #endregion #region 预先加载，懒加载 //预先加载(贪婪加载，饥饿加载，一次行加载所有) //var list = blogContext.Blog.Include(op => op.Posts).ThenInclude(op => op.Author).ToList(); //var list = blogContext.Blog.Include(op => op.Posts).ThenInclude(op => op.Author).ToList(); //var list = blogContext.Blog.Include(op => op.Posts).ThenInclude(op => op.Author).ToList().AsQueryable(); //foreach (var item in list) //{ // Console.WriteLine($"blog:{item}"); // foreach (var it in item.Posts) // { // Console.WriteLine($"Posts:{it.Title}"); // Console.WriteLine($"person:{it.Author.Name}"); // } //} //懒加载(延迟加载)，又称按需加载，net ef core 默认时候没有懒加载的， //ef是有的，ef core 要使用懒加载，需要使用proxy代理类UseLazyLoadingProxies，并且导航属性要添加Virtual标记 //optionsBuilder.UseLazyLoadingProxies() #endregion #region IQueryable和IEnumerable不同 //IQueryable和IEnumerable不同 //IQueryable和IEnumerable都是linq操作 //IQueryable和IEnumerable都是延迟执行，tolist的时候在执行 //只不过操作的位置不同，IQueryable是在数据库一侧操作，而IEnumerable实在应用程序的内存一侧操作， //IQueryable继承IEnumerable，IQueryable与IEnumerable 可以相互转换，IQueryable.AsIEnumerable,IEnumerable.AsIQueryable //var item = blogContext.Post.OrderBy(op => EF.Property<object>(op, "Title")).AsQueryable().Skip(1).Take(2); //IQueryable 在数据库中的 执行脚本，IQueryable和IEnumerable都是延迟执行，tolist的时候在执行 //exec sp_executesql N'SELECT [p].[PostId], [p].[BlogId], [p].[Content], [p].[PersonId], [p].[Title] //FROM[Post] AS[p] //ORDER BY[p].[Title] //OFFSET @__p_0 ROWS FETCH NEXT @__p_1 ROWS ONLY',N'@__p_0 int,@__p_1 int',@__p_0=1,@__p_1=2 //foreach (var it in item) //{ // Console.WriteLine($"it:{it.Title}"); //} //var item = blogContext.Post.OrderBy(op => op.Title).AsEnumerable().Skip(1).Take(2); //IEnumerable在内存中的 执行脚本，IQueryable和IEnumerable都是延迟执行，tolist的时候在执行 //SELECT[p].[PostId], [p].[BlogId], [p].[Content], [p].[PersonId], [p].[Title] //FROM[Post] AS[p] //ORDER BY[p].[Title] //foreach (var it in item) //{ // Console.WriteLine($"it:{it.Title}"); //} #endregion #region 实体跟踪Tracking //一种是全局修改之后在修改回来 //另外一种是，是使用AsNoTracking()直接修改 //blogContext.ChangeTracker.QueryTrackingBehavior = QueryTrackingBehavior.NoTracking; using (IDbContextTransaction transaction = blogContext.Database.BeginTransaction()) { //var item = blogContext.Post.Where(op => op.Title.Contains("10")); var item = blogContext.Post.AsNoTracking().Where(op => op.Title.Contains("10")); //foreach (var it in item) // { // Console.WriteLine($"it:{it.Title}"); // it.Title = "111"; // } // blogContext.SaveChanges(); transaction.Commit(); } //blogContext.ChangeTracker.QueryTrackingBehavior = QueryTrackingBehavior.TrackAll; #endregion #region 模糊查询StartsWith,,EndsWith,Contains,其中Contains和 EF.Functions.Like功能一样，但是sql语句翻译的确实不一样的 但凡使用的计算函数，索引是一定不会被用上的 //var item = blogContext.Post.Where(op => op.Title.Contains("10")).ToList(); SELECT[p].[PostId], [p].[BlogId], [p].[Content], [p].[PersonId], [p].[Title] FROM[Post] AS[p] WHERE CHARINDEX(N'10', [p].[Title]) > 0 //foreach (var it in item) //{ // Console.WriteLine($"it:{it.Title}"); //} //item = blogContext.Post.Where(op => EF.Functions.Like(op.Title, "%10%")).ToList(); SELECT[p].[PostId], [p].[BlogId], [p].[Content], [p].[PersonId], [p].[Title] FROM[Post] AS[p] WHERE[p].[Title] LIKE N'%10%' //foreach (var it in item) //{ // Console.WriteLine($"it:{it.Title}"); //} #endregion #region 自定义标量函数，linq一样可以翻译成对应的sql脚本 SELECT[p].[PostId] AS[id], [dbo].[MyFunction] ([p].[PostId]) AS[name] FROM[Post] AS[p] //var item = blogContext.Post.Select(op => new //{ // id = op.PostId, // name = BlogContext.MyFunction(op.PostId)//使用标量函数 //}).ToList(); //foreach (var it in item) //{ // Console.WriteLine($"it:{it.name}"); //} #endregion #region 编译查询 #region 普通查询 //int id = 1; //Stopwatch stopwatch = new Stopwatch(); //stopwatch.Start(); //var item = blogContext.Post.Where(op => op.PostId == id).FirstOrDefault(); //stopwatch.Stop(); //Console.WriteLine($"普通查询：item:{item.Title},用时：{stopwatch.ElapsedMilliseconds}"); // exec sp_executesql N'SELECT TOP(1) [p].[PostId], [p].[BlogId], [p].[Content], [p].[PersonId], [p].[Title] //FROM[Post] AS[p] //WHERE[p].[PostId] = @__id_0',N'@__id_0 int',@__id_0=1 #endregion #region 编译查询 //Stopwatch stopwatch = new Stopwatch(); //stopwatch.Start(); var compileQuery = EF.CompileQuery((BlogContext context, int id) => context.Post.Where(c => c.PostId == id).FirstOrDefault()); var item = compileQuery(blogContext, 1); //stopwatch.Stop(); //Console.WriteLine($"普通查询：item:{item.Title},用时：{stopwatch.ElapsedMilliseconds}"); #endregion //普通查询 Func<BlogContext, Blog> unCompileQuery = context => context.Blog.Include(c => c.Posts).Where(a => a.BlogId == 1).FirstOrDefault(); Stopwatch stopwatch = new Stopwatch(); stopwatch.Start(); Console.WriteLine("普通查询开始"); for (int i = 0; i < 100000; i++) { var a = unCompileQuery(blogContext); } stopwatch.Stop(); Console.WriteLine($"编译查询 用时：{stopwatch.ElapsedMilliseconds} 毫秒"); //编译查询 一般是大量数据查询，并且参数不变的情况下比较好，但是不能返回集合 //Stopwatch stopwatch = new Stopwatch(); //stopwatch.Start(); //Console.WriteLine("编译查询开始"); //var compileQuery = EF.CompileQuery((BlogContext context, int id) => context.Blog.Include(c => c.Posts).Where(a => a.BlogId == 1).FirstOrDefault()); //for (int i = 0; i < 100000; i++) //{ // var item = compileQuery(blogContext, 1); //} //stopwatch.Stop(); //Console.WriteLine($"编译查询 用时：{stopwatch.ElapsedMilliseconds} 毫秒"); #endregion //var item = blogContext.Post.Where(op => op.Title.Contains("10")); //foreach (var it in item) //{ // Console.WriteLine($"it:{it.Title}"); //} //var item = blogContext.Post.Where(op => EF.Functions.Like(op.Title,"10")); //foreach (var it in item) //{ // Console.WriteLine($"it:{it.Title}"); //} Console.Read(); } } public class BlogContext : DbContext { public DbSet<Blog> Blog { get; set; } public DbSet<Post> Post { get; set; } public static readonly ILoggerFactory loggerFactory = LoggerFactory.Create(builder => builder.AddConsole().AddDebug()); protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder) { //optionsBuilder.UseLoggerFactory(loggerFactory);//添加把数据库操作的信息输出到指定的控制台 //optionsBuilder.UseLazyLoadingProxies().UseSqlServer(@"server=127.0.0.1;database=mynetcore;user=sa;password=sa123;"); //Microsoft.EntityFrameworkCore.SqlServer optionsBuilder.UseSqlServer(@"server=127.0.0.1;database=mynetcore;user=sa;password=sa123;"); //Pomelo.EntityFrameworkCore.MySql //optionsBuilder.UseMySql(@"server=127.0.0.1;database=mynetcore;user=root;password=123456;"); } protected override void OnModelCreating(ModelBuilder modelBuilder) { List<Post> posts = new List<Post>(); for (int i = 0; i < 20; i++) { posts.Add(new Post { PostId = i + 1, PersonId = i >= 10 ? 2 : 1, Title = $"文章标题:100{i}", Content = $"文章内容:{i}", BlogId = i >= 10 ? 2 : 1 }); } Blog blogs = new Blog { BlogId = 1, Url = "http://www.baidu.com" }; Blog blogs1 = new Blog { BlogId = 2, Url = "http://www.tianmao.com" }; Person person = new Person { PersonId = 1, Name = "123" }; Person person1 = new Person { PersonId = 2, Name = "456" }; modelBuilder.Entity<Post>().HasData(posts); modelBuilder.Entity<Blog>().HasData(blogs, blogs1); modelBuilder.Entity<Person>().HasData(person, person1); } #region 自定义标量函数 [DbFunction] public static string MyFunction(int id) { throw new NotImplementedException(); } #endregion } public class Blog { public int BlogId { get; set; } public string Url { get; set; } public virtual List<Post> Posts { get; set; } } public class Post { public int PostId { get; set; } public string Title { get; set; } public string Content { get; set; } public int BlogId { get; set; } public virtual Blog Blog { get; set; } public int PersonId { get; set; } public virtual Person Author { get; set; } } public class Person { public int PersonId { get; set; } public string Name { get; set; } public virtual List<Post> Posts { get; set; } } }
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