如今是附加的，组合查询须要的扩展类。大家知道lanmda表达式的组合条件比較麻烦，所以就加了一样一个类，方便进行组合查询：

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Linq.Expressions;namespace JFrame.AccessCommon{    public static class PredicateExtensions    {        public static Expression
      
       
        > True
        
         ()        {            return f => true;        }        public static Expression
         
          
           > False
           
            () { return f => false; } public static Expression
            
             
              > Or
              
               (this Expression
               
                
                 > expression1, Expression
                 
                  
                   > expression2) { var invokedExpression = Expression.Invoke(expression2, expression1.Parameters.Cast
                   
                    ()); return Expression.Lambda
                    
                     
                      >(Expression.Or(expression1.Body, invokedExpression), expression1.Parameters); } public static Expression
                      
                       
                        > And
                        
                         (this Expression
                         
                          
                           > expression1, Expression
                           
                            
                             > expression2) { var invokedExpression = Expression.Invoke(expression2, expression1.Parameters.Cast
                             
                              ()); return Expression.Lambda
                              
                               
                                >(Expression.And(expression1.Body, invokedExpression), expression1.Parameters); } }}