如何使用asp.net跨数据库多表联合动态条件查询？针对这个问题，这篇文章详细介绍了相对应的分析和解答，希望可以帮助更多想解决这个问题的小伙伴找到更简单易行的方法。

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本文实例讲述了asp.net实现的MVC跨数据库多表联合动态条件查询功能。分享给大家供大家参考，具体如下：

一、控制器中方法

[HttpGet]
public ActionResult Search()
{
  ViewBag.HeadTitle = "搜索";
  ViewBag.MetaKey = "\"123\"";
  ViewBag.MetaDes = "\"456\"";
  string whereText = "";
  if (Security.HtmlHelper.GetQueryString("first", true) != string.Empty)
  {
    whereText += " and a.ParentId='" + StringFilter("first", true)+"'";
  }
  if (Security.HtmlHelper.GetQueryString("second", true) != string.Empty)
    whereText += " and a.categoryId='" + StringFilter("second",true)+"'";
  string valueStr = "";
  if (Security.HtmlHelper.GetQueryString("theme", true) != string.Empty)
    valueStr += StringFilter("theme", true) + ",";
  if (Security.HtmlHelper.GetQueryString("size", true) != string.Empty)
    valueStr += StringFilter("size", true) + ",";
  if (Security.HtmlHelper.GetQueryString("font", true) != string.Empty)
    valueStr += StringFilter("font", true) + ",";
  if (Security.HtmlHelper.GetQueryString("shape", true) != string.Empty)
    valueStr += StringFilter("shape", true) + ",";
  if (Security.HtmlHelper.GetQueryString("technique", true) != string.Empty)
    valueStr += StringFilter("technique", true) + ",";
  if (Security.HtmlHelper.GetQueryString("category", true) != string.Empty)
    valueStr += StringFilter("category", true) + ",";
  if (Security.HtmlHelper.GetQueryString("place", true) != string.Empty)
    valueStr += StringFilter("place", true) + ",";
  if (Security.HtmlHelper.GetQueryString("price", true) != string.Empty)
    valueStr += StringFilter("price", true) + ",";
  if (valueStr != "")
  {
    valueStr=valueStr.Substring(0, valueStr.Length - 1);
    whereText += " and f.valueId in("+valueStr+")";
  }
  if (Security.HtmlHelper.GetQueryString("searchKeys", true) != string.Empty)
    whereText += " and a.SaleTitle like '%'" + StringFilter("searchKes", true) + "'%' or a.SaleDes like '%'" + StringFilter("searchKes", true) + "'%' or a.SaleAuthor like '%'" + StringFilter("searchKes", true) + "'%' or a.KeyWords like '%'" + StringFilter("searchKes", true) + "'%' or g.valueProperty like '%'" + StringFilter("searchKes", true) + "'%'";
  int pageSize = 50;
  int pageIndex = HttpContext.Request.QueryString["pageIndex"].Toint(1);
  List searchInfo = Search(pageIndex, pageSize, whereText, 1);
  if (Security.HtmlHelper.GetQueryString("sort", true) != string.Empty)
  {
    string sort = StringFilter("sort", true);
    switch (sort)
    {
      case "1":  //综合即默认按照上架时间降序排列即按照id降序
        searchInfo = Search(pageIndex, pageSize, whereText, 1);
        break;
      case"2":  //销量
        searchInfo = Search(pageIndex, pageSize, whereText,0, "saleTotal");
        break;
      case "3":  //收藏
        searchInfo = Search(pageIndex, pageSize, whereText,0, "favoritesTotal");
        break;
      case "4":  //价格升序
        searchInfo = Search(pageIndex, pageSize, whereText,1);
        break;
      case "5":  //价格降序
        searchInfo = Search(pageIndex, pageSize, whereText,2);
        break;
    }
  }
  string jsonStr = searchInfo[0];
  ViewData["jsondata"] = jsonStr;
  int allCount = Utility.Toint(searchInfo[1], 0);
  ViewBag.AllCount = allCount;
  ViewBag.MaxPages = allCount % pageSize == 0 ? allCount / pageSize : (allCount / pageSize + 1).Toint(1);
  return View();
}
[NonAction]
public List Search(int pageIndex, int pageSize, string whereText, int orderByPrice, string orderBy = "SaleId")
{
  BLL.Products searchInfoBLL = new BLL.Products();
  List searchInfo = searchInfoBLL.GetSearchInfo(pageIndex, pageSize, whereText, orderByPrice,orderBy);
  return searchInfo;
}

注：Security.HtmlHelper.GetQueryString(），StringFilter(）为自己封装的方法，用于过滤参数值

二、BLL层方法

using System;
using System.Web;
using System.Web.Caching;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.Common;
using System.Web.Script.Serialization;
using FotosayMall.Model;
using FotosayMall.Common;
using System.Text.RegularExpressions;
using System.IO;
using Newtonsoft.Json;
using Newtonsoft.Json.Converters;
using FotosayMall.MVC.Models;
namespace FotosayMall.BLL
{
  public class Products
  {
    private readonly DAL.Products dal = new DAL.Products();
    /// 

    /// 分页查询，检索页数据
    /// 
    /// 
    /// 
    /// 价格排序：0默认，1升序，2降序
    /// 
    public List GetSearchInfo(int pageIndex, int pageSize, string whereText, int orderByPrice, string orderBy = "SaleId")
    {
      DataSet searchInfoTables = dal.GetSearchInfo(pageIndex, pageSize, whereText);
      //总记录数
      int allCount = Utility.Toint(searchInfoTables.Tables[1].Rows[0]["rowsTotal"], 0);
      var searchInfo = from list in searchInfoTables.Tables[0].AsEnumerable().OrderByDescending(x => x.Table.Columns[orderBy])
        select new SearchModel
        {
         Url = "/home/products?saleId=" + list.Field("SaleId"),
         Author = list.Field("SaleAuthor"),
         PhotoFileName = list.Field("PhotoFileName"),
         PhotoFilePathFlag = list.Field("PhotoFilePathFlag"),
         Province = list.Field("Place").Split(' ').First(),
         SalePrice = list.Field("SalePrice"),
         UsingPrice = list.Field("usingPrice"),
         Title = list.Field("SaleTitle").Length > 30 ? list.Field("SaleTitle").Substring(0, 30) : list.Field("SaleTitle"),
         Year = list.Field("BuildTime").ToString("yyyy") == "1900" ? "" : list.Field("BuildTime").ToString("yyyy年")
        };
      if (orderByPrice==2)
        searchInfo = searchInfo.OrderByDescending(x => x.Price);
      else if (orderByPrice == 1)
        searchInfo = searchInfo.OrderBy(x => x.Price);
      string jsonStr = JsonConvert.SerializeObject(searchInfo);
      List dataList = new List();
      dataList.Add(jsonStr);
      dataList.Add(allCount.ToString());
      return dataList;
    }
  }
}

注：注意观察由DataTable转换为可枚举的可用于Linq查询的方法方式。

DAL

/// 

/// 获取检索页数据
/// 
/// 
/// 
/// 
public DataSet GetSearchInfo(int pageIndex, int pageSize, string whereText)
{
  StringBuilder sqlText = new StringBuilder();
  sqlText.Append("select * from (");
  sqlText.Append("select a.SaleId,a.PhotoId,SaleTitle,SaleAuthor,a.Status,a.categoryId,c.UserID,c.UserName,b.PhotoFilePathFlag,b.PhotoFileName,coalesce(e.BuildTime,0) BuildTime,c.Place,coalesce(d.usingPrice,0) usingPrice,coalesce(e.SalePrice,0) SalePrice,h.saleTotal,h.favoritesTotal,row_number() over(order by a.saleId) rowsNum ");
  sqlText.Append("from fotosay..Photo_Sale a join fotosay..Photo_Basic b on a.PhotoId = b.PhotoID ");
  sqlText.Append("join fotosay..System_AccountsDescription c on b.UserID = c.UserID ");
  sqlText.Append("left join fotosay..Photo_Sale_Picture d on a.SaleId = d.SaleId ");
  sqlText.Append("left join fotosay..Photo_Sale_Tangible e on a.saleId = e.saleId ");
  sqlText.Append("join FotosayMall..Fotomall_Product_Relation f on f.saleId = a.SaleId ");
  sqlText.Append("join FotosayMall..Fotomall_Product_PropertyValue g on g.categoryId = a.categoryId and g.valueId = f.valueId and g.propertyId = f.propertyId ");
  sqlText.Append("join fotosay..Photo_Sale_Property h on a.saleId = h.saleId ");
  sqlText.Append("where a.Status=1 " + whereText + " ");
  sqlText.Append("group by a.SaleId,a.PhotoId,SaleTitle,SaleAuthor,a.Status,a.categoryId,c.UserID,c.UserName,b.PhotoFilePathFlag,b.PhotoFileName,e.BuildTime,c.Place,usingPrice,SalePrice,h.saleTotal,h.favoritesTotal ");
  sqlText.Append(") t where rowsNum between @PageSize*(@PageIndex-1)+1 and @PageSize*@PageIndex;");
  sqlText.Append("select count(distinct a.saleId) rowsTotal from fotosay..Photo_Sale a join (select b1.PhotoFilePathFlag,b1.PhotoFileName,b1.UserID,b1.PhotoID from fotosay..Photo_Basic b1 union select b2.PhotoFilePathFlag,b2.PhotoFileName,b2.UserID,b2.PhotoID from fotosay..Photo_Basic_History b2 ) b on a.PhotoId = b.PhotoID join fotosay..System_AccountsDescription c on b.UserID = c.UserID left join fotosay..Photo_Sale_Picture d on a.SaleId = d.SaleId left join fotosay..Photo_Sale_Tangible e on a.saleId = e.saleId join FotosayMall..Fotomall_Product_Relation f on f.saleId = a.SaleId join FotosayMall..Fotomall_Product_PropertyValue g on g.categoryId = a.categoryId and g.valueId = f.valueId and g.propertyId = f.propertyId join fotosay..Photo_Sale_Property h on a.saleId = h.saleId where a.Status=1 " + whereText + ";");
  DbParameter[] parameters = {
    Fotosay.CreateInDbParameter("@PageIndex", DbType.Int32,pageIndex),
    Fotosay.CreateInDbParameter("@PageSize", DbType.Int32,pageSize)
    };
  DataSet searchInfoList = Fotosay.ExecuteQuery(CommandType.Text, sqlText.ToString(), parameters);
  //记录条数不够一整页,则查历史库
  if (searchInfoList.Tables[0].Rows.Count < pageSize)
  {
    string sql = "select top(1) a.saleId from fotosay..Photo_Sale a join fotosay..Photo_Basic_History b on a.PhotoId = b.PhotoID join fotosay..System_AccountsDescription c on b.UserID = c.UserID left join fotosay..Photo_Sale_Picture d on a.SaleId = d.SaleId left join fotosay..Photo_Sale_Tangible e on a.saleId = e.saleId join FotosayMall..Fotomall_Product_Relation f on f.saleId = a.SaleId join FotosayMall..Fotomall_Product_PropertyValue g on g.categoryId = a.categoryId and g.valueId = f.valueId and g.propertyId = f.propertyId join fotosay..Photo_Sale_Property h on a.saleId = h.saleId where a.Status=1 " + whereText + ";";
    DataSet ds = Fotosay.ExecuteQuery(CommandType.Text, sql.ToString(), parameters);
    if (ds != null && ds.Tables[0].Rows.Count > 0)
    {
      StringBuilder sqlTextMore = new StringBuilder();
      sqlTextMore.Append("select * from (");
      sqlTextMore.Append("select a.SaleId,a.PhotoId,SaleTitle,SaleAuthor,a.Status,a.categoryId,c.UserID,c.UserName,b.PhotoFilePathFlag,b.PhotoFileName,coalesce(e.BuildTime,0) BuildTime,c.Place,coalesce(d.usingPrice,0) usingPrice,coalesce(e.SalePrice,0) SalePrice,h.saleTotal,h.favoritesTotal,row_number() over(order by a.saleId) rowsNum ");
      sqlTextMore.Append("from fotosay..Photo_Sale a ");
      sqlTextMore.Append("join (select b1.PhotoFilePathFlag,b1.PhotoFileName,b1.UserID,b1.PhotoID from fotosay..Photo_Basic b1 union select b2.PhotoFilePathFlag,b2.PhotoFileName,b2.UserID,b2.PhotoID from fotosay..Photo_Basic_History b2 ) b on a.PhotoId = b.PhotoID join fotosay..System_AccountsDescription c on b.UserID = c.UserID ");
      sqlTextMore.Append("left join fotosay..Photo_Sale_Picture d on a.SaleId = d.SaleId ");
      sqlTextMore.Append("left join fotosay..Photo_Sale_Tangible e on a.saleId = e.saleId ");
      sqlTextMore.Append("join FotosayMall..Fotomall_Product_Relation f on f.saleId = a.SaleId ");
      sqlTextMore.Append("join FotosayMall..Fotomall_Product_PropertyValue g on g.categoryId = a.categoryId and g.valueId = f.valueId and g.propertyId = f.propertyId ");
      sqlTextMore.Append("join fotosay..Photo_Sale_Property h on a.saleId = h.saleId ");
      sqlTextMore.Append("where a.Status=1 " + whereText + " ");
      sqlTextMore.Append("group by a.SaleId,a.PhotoId,SaleTitle,SaleAuthor,a.Status,a.categoryId,c.UserID,c.UserName,b.PhotoFilePathFlag,b.PhotoFileName,e.BuildTime,c.Place,usingPrice,SalePrice,h.saleTotal,h.favoritesTotal");
      sqlTextMore.Append(") t where rowsNum between @PageSize*(@PageIndex-1)+1 and @PageSize*@PageIndex;");
      sqlTextMore.Append("select count(distinct a.saleId) rowsTotal from fotosay..Photo_Sale a join (select b1.PhotoFilePathFlag,b1.PhotoFileName,b1.UserID,b1.PhotoID from fotosay..Photo_Basic b1 union select b2.PhotoFilePathFlag,b2.PhotoFileName,b2.UserID,b2.PhotoID from fotosay..Photo_Basic_History b2 ) b on a.PhotoId = b.PhotoID join fotosay..System_AccountsDescription c on b.UserID = c.UserID left join fotosay..Photo_Sale_Picture d on a.SaleId = d.SaleId left join fotosay..Photo_Sale_Tangible e on a.saleId = e.saleId join FotosayMall..Fotomall_Product_Relation f on f.saleId = a.SaleId join FotosayMall..Fotomall_Product_PropertyValue g on g.categoryId = a.categoryId and g.valueId = f.valueId and g.propertyId = f.propertyId join fotosay..Photo_Sale_Property h on a.saleId = h.saleId where a.Status=1 " + whereText + ";");
      searchInfoList = Fotosay.ExecuteQuery(CommandType.Text, sqlTextMore.ToString(), parameters);
    }
  }
  return searchInfoList;
}

注：注意其中使用的跨数据库查询的方式和union的一种使用方式

Model

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Web;
namespace FotosayMall.MVC.Models
{
  public class SearchModel
  {
    /// 

    /// 原始图片文件夹(用于url地址)
    /// 
    private const string OriginImagesUrlFolder = "userimages/photos_origin";
    /// 

    /// 购买页链接
    /// 
    public string Url { get; set; }
    /// 

    /// 所属域名(1为fotosay，2为img，3为img1)
    /// 
    public int PhotoFilePathFlag { get; set; }
    /// 

    /// 图片名称
    /// 
    public string PhotoFileName { get; set; }
    /// 

    /// 商品名称
    /// 
    public string Title { get; set; }
    /// 

    /// 作者所在省份
    /// 
    public string Province { get; set; }
    /// 

    /// 作者
    /// 
    public string Author { get; set; }
    /// 

    /// 创作年份
    /// 
    public string Year { get; set; }
    /// 

    /// 图片：单次价格
    /// 
    public decimal UsingPrice { get; set; }
    /// 

    /// 实物：定价
    /// 
    public decimal SalePrice { get; set; }
    /// 

    /// 售价
    /// 
    public string Price
    {
      get
      {
        if (this.UsingPrice > 0)
          return this.UsingPrice.ToString();
        else if (this.SalePrice > 0)
          return this.SalePrice.ToString();
        else
          return "议价";
      }
    }
    /// 

    ///
    /// 
    private string MasterSite
    {
      get { return ConfigurationManager.AppSettings["masterSite"].ToString(); }
    }
    /// 

    /// 图片完整路径
    /// 
    public string Img
    {
      get
      {
        return MasterSite + "/" + OriginImagesUrlFolder + this.PhotoFileName + "b.jpg";
      }
    }
  }
}

关于如何使用asp.net跨数据库多表联合动态条件查询问题的解答就分享到这里了，希望以上内容可以对大家有一定的帮助，如果你还有很多疑惑没有解开，可以关注创新互联行业资讯频道了解更多相关知识。

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