代码如下：

public class LinqDatabase : MonoBehaviour
{
    [Serializable]
    public class Supplier
    {

        public string Name;
        public string District;
        public int Age;

    }

    [Serializable]
    public class Buyer
    {
        public string Name;
        public string District;
        public int Age;
    }

    [SerializeField] private List<Buyer> _buyers = new List<Buyer>();
    [SerializeField] private List<Supplier> _supplier = new List<Supplier>();

    void Start ( )
    {
        var leftOuterJJoin = from s in _supplier
            join b in _buyers on s.District equals b.District into NewbuyersGroup
            from BG in NewbuyersGroup.DefaultIfEmpty()
            select new
            {
                s.Name, s.District,
                BuyersName = BG?.Name ?? "No one here"
            };

        foreach ( var VARIABLE in leftOuterJJoin )
        {
            Debug.Log ( $"{VARIABLE.Name} {VARIABLE.District}" );
            Debug.Log ( VARIABLE.BuyersName );
        }
    }
}

我的问题是，如果你比较列表，它应该输出no one here for S5w和TTW mkm，因为在地区中没有匹配。但是，DefaultIfEmpty似乎不适用于整个列表，而只适用于第一个不匹配的对象（S4ko）。我如何将no one here应用于所有不匹配的地区？