SQL强类型查询的许多实现方法都不够直观，下面的实现方法是一个直观的SQL强类型查询，供您参考，希望对您有所启示。
这里只是个验证想法的代码,所以没有作任何容错和扩展性处理.也不要提出OO不OO的看法,毫无疑义.
所设想的是一个查询 Select [Columnlist] From [TableName] Where [Exp] Order By [PK] 一般来说是这个格式，我们最难表述的其实就是[Exp]这个部分。前面的都比较格式化，所以可以通过嵌套方法来实现还是比较合适的，但是[Exp]这个部分用诸如AND(Exp1,Exp2)这样子的形式不能很直观的看出表达式的意义，所以通过重载操作符的方式来实现，这里我们假设在Entity的Class里有static成员来存储列的名称。那么
Exp Rs=new Exp(User.ID) == 2 & new Exp(User.State) > 0 ;
这样子的格式就能表达Where后面的 ID=2 AND State>0 这个表达式
具体代码如下
class Program 2 { 3 static void Main(string[] args) 4 { 5 6 Exp rs = new Exp("C1") == 25 & new Exp("C2") > 3 | new Exp("C3") < 5 ^ new Exp("C4") % "hehe"; 7 Console.WriteLine(rs.Sql); 8 foreach (SqlParameter sp in rs.Sps) 9 { 10 Console.WriteLine(sp.ParameterName); 11 } 12 Console.Read(); 13 } 14 } 15 16 class Exp 17 { 18 private string _Sql; 19 20 private List<SqlParameter> sps; 21 22 public List<SqlParameter> Sps 23 { 24 get { return sps; } 25 set { sps = value; } 26 } 27 28 private SqlParameter sp; 29 30 public string Sql 31 { 32 get { return _Sql; } 33 } 34 35 private Exp() 36 { 37 sps = new List<SqlParameter>(); 38 } 39 40 public Exp(string CollumnName) 41 { 42 _Sql = CollumnName; 43 } 44 45 public static Exp operator ==(Exp Left, Object Value) 46 { 47 Exp Next = new Exp(); 48 Next.sp = new SqlParameter(Left._Sql, Value); 49 Next.sps.Add(Next.sp); 50 Next._Sql = Left._Sql + " = @" + Left.Sql; 51 return Next; 52 } 53 public static Exp operator !=(Exp Left, Object Value) 54 { 55 Exp Next = new Exp(); 56 Next.sp = new SqlParameter(Left._Sql, Value); 57 Next.sps.Add(Next.sp); 58 Next._Sql = Left._Sql + " <> @" + Left._Sql; 59 return Next; 60 } 61 62 public static Exp operator <(Exp Left, Object Value) 63 { 64 Exp Next = new Exp(); 65 Next.sp = new SqlParameter(Left._Sql, Value); 66 Next.sps.Add(Next.sp); 67 Next._Sql = Left._Sql + " < @" + Left._Sql; 68 return Next; 69 } 70 public static Exp operator >(Exp Left, Object Value) 71 { 72 Exp Next = new Exp(); 73 Next.sp = new SqlParameter(Left._Sql, Value); 74 Next.sps.Add(Next.sp); 75 Next._Sql = Left._Sql + " > @" + Left._Sql; 76 return Next; 77 } 78 79 public static Exp operator %(Exp Left, Object Value) 80 { 81 Exp Next = new Exp(); 82 Next.sp = new SqlParameter(Left._Sql, Value); 83 Next.sps.Add(Next.sp); 84 Next._Sql = Left._Sql + " Like @" + Left._Sql; 85 return Next; 86 } 87 88 public static Exp operator &(Exp Left, Exp Right) 89 { 90 Exp Next = new Exp(); 91 foreach (SqlParameter sp in Left.sps) 92 { 93 Next.sps.Add(sp); 94 } 95 foreach (SqlParameter sp in Right.sps) 96 { 97 Next.sps.Add(sp); 98 } 99 Next._Sql = Left.Sql + " AND " + Right.Sql; 100 return Next; 101 } 102 103 104 public static Exp operator |(Exp Left, Exp Right) 105 { 106 Exp Next = new Exp(); 107 foreach (SqlParameter sp in Left.sps) 108 { 109 Next.sps.Add(sp); 110 } 111 foreach (SqlParameter sp in Right.sps) 112 { 113 Next.sps.Add(sp); 114 } 115 Next._Sql = Left.Sql + " OR " + Right.Sql; 116 return Next; 117 } 118 119 public static Exp operator ^(Exp Left, Exp Right) 120 { 121 Exp Next = new Exp(); 122 foreach (SqlParameter sp in Left.sps) 123 { 124 Next.sps.Add(sp); 125 } 126 foreach (SqlParameter sp in Right.sps) 127 { 128 Next.sps.Add(sp); 129 } 130 Next._Sql = Left.Sql + " NOT " + Right.Sql; 131 return Next; 132 } 133 } 134