net-core(EF Core)-使用表达式树还是委托

using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata.Builders;

public class MemberConfig : IEntityTypeConfiguration<Member>
{
    public void Configure(EntityTypeBuilder<Member> builder)
    {
        builder.ToTable("T_Member").HasKey(k => k.Id);

        builder.Property(c => c.Address).HasMaxLength(255);
        builder.Property(c => c.E_mail).HasMaxLength(100);
    }

}

public class Member{
    public int Id{get;set;}
    public string E_mail{get;set;}
    public string Name{get;set;}
    public string Address{get;set;}
}

using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Console;

public class MyDbContext : DbContext
{

    public DbSet<Member> members { get; set; } // 
    public static readonly ILoggerFactory consoleLoggerFactory
          = LoggerFactory.Create(config=>config.AddConsole());

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        base.OnConfiguring(optionsBuilder);
        var serverVersion = new MySqlServerVersion(new Version(8, 0, 27));
        optionsBuilder
           .UseMySql(
            "Server=127.0.0.1;port=3306;Database=YBDDataBase;uid=root;pwd=ybdai930728;Character Set=utf8;"
           , serverVersion)
           //.UseLoggerFactory(consoleLoggerFactory);
           .LogTo(Console.WriteLine, LogLevel.Information)
           .EnableSensitiveDataLogging()
           .EnableDetailedErrors();
    }
    // 这个是不能少的。
    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);
        modelBuilder.ApplyConfigurationsFromAssembly(this.GetType().Assembly);
    }
}

如果是web项目

builder.Services.AddDbContext<MemberDbContext>();

关于使用表达式和委托的区别：

Expression<Func<Member,bool>> a1 = (c) =>  c.Address.Contains("q");

Func<Member,bool> f1 = (c) => c.Address.Contains("q");

using var db = new MyDbContext();
var s = db.members.Where(a1); 
var s2 = db.members.Where(f1);
System.Console.WriteLine("hello world!");

两者生成的sql如下：

Expression:
SELECT `t`.`Id`, `t`.`Address`, `t`.`E_mail`, `t`.`Name`
      FROM `T_Member` AS `t`
      WHERE `t`.`Address` LIKE '%q%'
Func:
SELECT `t`.`Id`, `t`.`Address`, `t`.`E_mail`, `t`.`Name`
      FROM `T_Member` AS `t`