Linq To Sql的各种查询

一、Inner Join

  //request为查询条件

  var result = from a in db.TableA

 join b in db.TableB

 on a.ID equals b.ID

 where a.UserName == request.UserName || a.Mobile == request.Mobile

 select new ResponseInfo

 {

     UserName = ui.UserName,

     UserID = ui.ID,

     Mobile = ui.Mobile,

     Value = ue.Value

 };

 

二、Left  Join

//request为查询条件

var result = from si in db.TableA

     join ai in db.TableB on si.UserID equals ai.ID into ljTableB

     from ai in ljTableB.DefaultIfEmpty()

     join pi in db.TableC on si.ProductID equals pi.ID into ljTableC

     from pi in ljTableC.DefaultIfEmpty()

     join ps in db.TableD on si.SpecID equals ps.ID into ljTableD

     from ps in ljTableD.DefaultIfEmpty()

     select new InfoResposne

     {

         ID = si.ID,

         DisplayID = pi.DisplayID,

         ProductID = si.ProductID,

         ProductName = pi.ProductName,

         BarCode = pi.BarCode,

         SpecID = si.SpecID,

         Created = si.Created

     };

 

二、动态添加查询条件及翻页

//字符串

if (!string.IsNullOrWhiteSpace(request.DisplayID))

{

    result = result.Where(p => p.DisplayID == request.DisplayID);

}

//字符串包含

if (!string.IsNullOrWhiteSpace(request.UserName))

{

    userInfo = userInfo.Where(p => p.UserName.Contains(request.UserName));

}

//数字、状态类型

if (request.Amount!=null)

{

    result = result.Where(p => p.Amount == request.Amount);

}

//时间范围

  if (request.StockInStart != null)

{

    result = result.Where(p => p.Created >= request.StockInStart);

}

//时间范围

if (request.StockInEnd != null)

{

    result = result.Where(p => p.Created <= request.StockInEnd);

}

 

var response = new LogResponse();

response.TotalCount = result.Count();

response.DataList = result

            .OrderByDescending(p => p.Created)

            .Skip((request.PageIndex - 1) * request.PageSize)

            .Take(request.PageSize)

            .ToList();