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1.多条件OR使用实例：

//学费if (string.IsNullOrEmpty(tuition) == false && tuition != "0"){    Expression
   
    
     > orQuery = q => false;    foreach (var item in tuitionID)    {        Tuition tui = Tuition.GetMode(item);        orQuery = orQuery.Or(q => q.TuitionFee >= tui.MinValue && q.TuitionFee < tui.MaxValue);    }    query = query.Where(orQuery);}
    
   

2.添加扩展方法

public static class Utility    {        public static Expression
   
     Compose
    
     (this Expression
     
       first, Expression
      
        second, Func
       
         merge)        {            // build parameter map (from parameters of second to parameters of first)            var map = first.Parameters.Select((f, i) => new { f, s = second.Parameters[i] }).ToDictionary(p => p.s, p => p.f);            // replace parameters in the second lambda expression with parameters from the first            var secondBody = ParameterRebinder.ReplaceParameters(map, second.Body);            // apply composition of lambda expression bodies to parameters from the first expression            return Expression.Lambda
        
         (merge(first.Body, secondBody), first.Parameters); } public static Expression
         
          
           > And
           
            (this Expression
            
             
              > first, Expression
              
               
                > second) { return first.Compose(second, Expression.And); } public static Expression
                
                 
                  > Or
                  
                   (this Expression
                   
                    
                     > first, Expression
                     
                      
                       > second) { return first.Compose(second, Expression.Or); } } public class ParameterRebinder : ExpressionVisitor { private readonly Dictionary
                       
                         map; public ParameterRebinder(Dictionary
                        
                          map) { this.map = map ?? new Dictionary
                         
                          (); } public static Expression ReplaceParameters(Dictionary
                          
                            map, Expression exp) { return new ParameterRebinder(map).Visit(exp); } protected override Expression VisitParameter(ParameterExpression p) { ParameterExpression replacement; if (map.TryGetValue(p, out replacement)) { p = replacement; } return base.VisitParameter(p); } }
                          
                         
                        
                       
                      
                     
                    
                   
                  
                 
                
               
              
             
            
           
          
         
        
       
      
     
    
   

更多参考：

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