Entity Framework with MySQL 学习笔记一(常用小总结)

1-1 设置

　　 //DataAnnotation 1-1 | 1-0 table
    //SQLtable : member , columns : memberId, name
    //SQL basic logic : 1个table的PK, 是另一个table的PK and FK , 这就是1-1和1-0的关系
    [Table("member")]
    public class Member
    {
        [Key]
        public Int32 memberId { get; set; }
        public string name { get; set; }
        [Required]
        /*
            1-0,这里就不要Required
            1-1关系最好是放Required啦，在insert的时候才不会出错，但是...
            如果你写Required,那么你在做update的时候这个address不能是Null,也就是说一定要inner join出来先，不是很方便.
        */
        public virtual Address address { get; set; }
    }
    //SQLtable : address , columns : memberId, postcode, country
    [Table("address")]
    public class Address
    {
        /*
            关键就是这个关系连接, "member" 是 tableName
        */
        [Key, ForeignKey("member")]
        public Int32 addressId { get; set; } //这里取名addressId也行
        public string postcode { get; set; }
        public string country { get; set; }
        public virtual Member member { get; set; }
    }

基本的 CRUD

using (EFDB db = new EFDB())
{
    /*insert*/
    db.members.Add(new Member
    {
        name = "keatkeat",
        address = new Address
        {
            postcode = "81300",
            country = "malaysia"
        }
    });
    db.SaveChanges();

    /*select*/
    var members = db.members.Include(m => m.address).ToList(); //要include才会一起出来哦 

    /*update*/
    var member = db.members.Include(m => m.address).First().name = "xinyao123";
    db.SaveChanges();

    /*delete*/
    db.members.Remove(db.members.Include(m => m.address).First()); //要include出来才能一次删除2个table的数据！
    db.SaveChanges();
}

1-n 设置

    //1-n
    /*
        基本上如果没有必要就不要写required了，这样比较方便在update单个table的时候.(insert的时候自己要控制好！)
    */
    [Table("prod")]
    public class Prod
    {
        [Key]
        public Int32 prodId { get; set; }
        public string code { get; set; }
        public virtual ICollection<Color> colors { get; set; } //有多个colors，用ICollection | List 也可以
    }
    [Table("color")]
    public class Color
    {
        [Key]
        public Int32 colorId { get; set; }
        [ForeignKey("prod")] //指定一个FK
        public Int32 prodId { get; set; }
        public string color { get; set; }
        public virtual Prod prod { get; set; } //有一个prod
    }