如果通过开头字字符串来获取相应的最高值？

[qjw9004]

我有一数据：

contractNO（字段）
AX-001
AX-002
AX-003
BYT-001
BYT-002
CD-01
CD-02

如何获取最大值？
string classNO
当classNO=“CD”时，取值为：CD-02
当classNO=“AX”时，取值为：AX-003
当classNO=“BYT”时，取值为：BYT-002
当classNO=“RE”时，取值为：NULL
下面是我写了一点不知什么弄了！请指点，谢谢

var query = from c in db.ConditionsContracts
where c.contractNO.StartsWith(classNO)
orderby c.contractNO
select c;

[Poopaye]

orderby int.Parse(c.contractNO.SubString(classNO.Length + 1)) descending

[Poopaye]

var query = (from c in db.ConditionsContracts
where c.contractNO.StartsWith(classNO)
orderby int.Parse(c.contractNO.SubString(classNO.Length + 1)) descending 
select c)
.First();

[q107770540]

var query = (from c in db.ConditionsContracts
	     where c.contractNO.StartsWith(classNO)
             orderby int.Parse(Regex.Match(c.contractNO,@"(?<=-)\d+").Value) descending 
             select c).FirstOrDefault();

[cxmcxm]

List<string> li = new List<string>();
        li.AddRange(new[] { "AX-001", "AX-002", "AX-003", "BYT-001", "BYT-002", "CD-01", "CD-02" });
        var q = from c in li
                group c by c.Split('-')[0] into d
                select new { classno = d.Key, maxno = d.Max() };

[Hertz_liu]

string[] testAry = new string[] { "AX-001", "AX-002", "AX-003", "BYT-001", "BYT-002", "CD-01", "CD-02" };
var result = from key in testAry
		     group key by key.Split('-')[0] into g
		     select g.Max();
foreach (var item in result)
{
          Console.WriteLine(item);
}

// 输出
// AX-003
// BYT-002
// CD-02