postgres entityframework foreignkey

    public class Model
    {
        [Key, Column("id"), DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public long Id { get; set; }
        [Column("create_time")]
        public DateTime CreTime { get; set; } = DateTime.Now;
        [Column("create_uid")]
        public long? CreUid { get; set; }
        [Column("update_time")]
        public DateTime? UpdTime { get; set; }
        [Column("update_uid")]
        public long? UpdUid { get; set; }
        [Column("remark")]
        public string Remark { get; set; }
        [Column("is_del")]
        public bool IsDel { get; set; } = false;
    }

    [Table("a_user_type")]
    public class UserCls
    {
        [Key, Column("id"), DatabaseGenerated(DatabaseGeneratedOption.None)]
        public long Id { get; set; }
        [Column("des")]
        public string Des { get; set; }
    }

    [Table("b_user")]
    public class User : Model
    {
        [Column("account"), Index(IsUnique = false)]
        public string Account { get; set; }
        [Column("passwd")]
        public string Passwd { get; set; }
        [Column("label")]
        public string Label { get; set; }
        [Column("cls_id"), ForeignKey("Cls")]
        public long? ClsId { get; set; }
        public virtual UserCls Cls { get; set; }
    }

以上数据库字段全部取小写，是因为postgres非常严格，驼峰式写法的sql要加双引号，非常麻烦。

mssqlserver 可以完全不用管，mysql只需注意表的名字小写即可，postgres连字段名都要特别注意。

    public class MesDbContext: DbContext
    {
        public MesDbContext():base("name=mes")
        {
            Database.SetInitializer(new MigrateDatabaseToLatestVersion<MesDbContext, MigrateConfig>());
        }

        public DbSet<User> Users { get; set; }
        public DbSet<UserCls> UserCls { get; set; } 
    }

    public class MigrateConfig : DbMigrationsConfiguration<MesDbContext>
    {
        public MigrateConfig()
        {
            AutomaticMigrationsEnabled = true;
            AutomaticMigrationDataLossAllowed = true;
        }
    }

  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework" />
    <providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
      <provider invariantName="Npgsql" type="Npgsql.NpgsqlServices, EntityFramework6.Npgsql" />
    </providers>
  </entityFramework>
  

  <system.data>
    <DbProviderFactories>
      <!--  注意这里，安装程序包时，这里的配置并不会自动添加  -->
      <remove invariant="Npgsql" />
      <add name="Npgsql" invariant="Npgsql" description=".Net Framework Data Provider for Postgresql" type="Npgsql.NpgsqlFactory, Npgsql" />
    </DbProviderFactories>
  </system.data>
  

<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="EntityFramework" version="6.2.0" targetFramework="net45" />
  <package id="EntityFramework6.Npgsql" version="3.1.1" targetFramework="net45" />
  <package id="Npgsql" version="3.2.5" targetFramework="net45" />
  <package id="System.Threading.Tasks.Extensions" version="4.4.0" targetFramework="net45" />
</packages>