asp.net用三层实现多条件检索示例

public class SearchModel 
{ 
public string Name { get; set; }//记录数据库字段名 
public string Value { get; set; }//记录对应的值 
public Action Action { get; set; }//记录相应的操作 
}

public enum Action 
{ 
Lessthan, 
Greatthan, 
Like, 
Equart 
}

List<SearchModel> ss = new List<SearchModel>(); 
if (!string.IsNullOrEmpty(Request.Form["txtName"]))//如果用户在名字框中输入了文字 
{ 
SearchModel model = new SearchModel(); 
model.Name = "BookName";//要操作的字段为书名 
model.Value = Request.Form["txtName"];//对应的值为用户输入的文字 
model.Action = Action.Like;//操作为like 
ss.Add(model); 
}//以下类似 
if (!string.IsNullOrEmpty(Request.Form["txtAuthor"])) 
{ 
SearchModel model = new SearchModel(); 
model.Name = "Author"; 
model.Value = Request.Form["txtAuthor"]; 
model.Action = Action.Like; 
ss.Add(model); 
} 
if (!string.IsNullOrEmpty(Request.Form["categoryId"])) 
{ 
SearchModel model = new SearchModel(); 
model.Name = "CategoryId"; 
model.Value = Request.Form["categoryId"]; 
model.Action = Action.Equart; 
ss.Add(model); 
} 
if (!string.IsNullOrEmpty(Request.Form["publisherId"])) 
{ 
SearchModel model = new SearchModel(); 
model.Name = "PublisherId"; 
model.Value = Request.Form["publisherId"]; 
model.Action = Action.Equart; 
ss.Add(model); 
} 
if (!string.IsNullOrEmpty(Request.Form["txtISBN"])) 
{ 
SearchModel model = new SearchModel(); 
model.Name = "ISBN"; 
model.Value = Request.Form["txtISBN"]; 
model.Action = Action.Like; 
ss.Add(model); 
} 
if (!string.IsNullOrEmpty(Request.Form["isDiscount"])) 
{ 
SearchModel model = new SearchModel(); 
model.Name = "Discount"; 
model.Value = "1"; 
model.Action = Action.Equart; 
ss.Add(model); 
} 
List<T_Books> books = searchBll.Searc(ss);//这里调用Bll进行操作

public List<T_Books> Search(List<SearchModel> ss)//接收传进来的条件模型类集合，并对其进行遍历 
{ 
string sql = "select  from T_Books where IsDelete=0 and ";//开始拼接sql语句 
for (int i = 0; i < ss.Count; i++) 
{ 
if (ss[i].Action == Action.Like) 
{ 
sql += ss[i].Name + " like '%" + ss[i].Value + "%'"; 
} 
if (ss[i].Action == Action.Equart) 
{ 
sql += ss[i].Name + " = " + ss[i].Value; 
} 
if (ss[i].Action == Action.Greatthan) 
{ 
sql += ss[i].Name + " > " + ss[i].Value; 
} 
if (ss[i].Action == Action.Lessthan) 
{ 
sql += ss[i].Name + " < " + ss[i].Value; 
} 
if (i != ss.Count - 1) 
{ 
sql += " and "; 
} 
} 
List<T_Books> list = new List<T_Books>(); 
DataTable table = SqlHelper.ExecuteDataTable(sql, CommandType.Text);//将拼接好的sql语句传入，开始查询数据库 
foreach (DataRow row in table.Rows) 
{ 
T_Books book = GetModelByDataRow.GetBooks(row); 
list.Add(book); 
} 
return list;//返回符合条件的图书集合，完成

select  from T_Books where IsDelete=0 and BookName like '%C++%' and Author like '%JChubby%' and CategoryId = 15 and PublisherId = 16 and ISBN like '%1111%' and Discount = 1