将具有多个左外连接和各种子句的 SQL 语句转换为 LINQ

Question

我一直在尝试创建关联和导航属性来稍微简化我的 LINQ 查询；但是，由于我正在使用复杂的专有数据库，这真的很困难。

在这个过程的大部分时间里，我一直在 EF5 上使用数据库优先方法。我无法先使用数据库创建关联和导航属性，所以我尝试在 SQL Server 上创建外键，但没有成功。

下一步，我尝试使用代码优先方法创建表、关联和导航属性；然而，同样，由于我正在使用的数据库和服务器的必要性，我未能成功简化我的查询。

我最后的手段就是做我最初在这个问题上想做的事情。也就是得到这个LINQ查询：

from item in db2.OrderFormDump
join icp in db2.IcPricP on item.NODASHITEMNO equals icp.ITEMNO into icpGroup
from iG in icpGroup.DefaultIfEmpty()
join itemInfo in db2.WebItemInfo on item.ITEMNO equals itemInfo.ITEMNO into itemInfoGroup
from iIG in itemInfoGroup.DefaultIfEmpty()
join weboeordh in db2.WebOEOrdH on "brian" equals weboeordh.USER into weboeordhGroup
from wOEODHG in weboeordhGroup.DefaultIfEmpty()
join weboeordd in db2.WebOEOrdD on new { itemno = item.NODASHITEMNO, orduniq = wOEODHG.ORDUNIQ } equals new { itemno = weboeordd.ITEMNO, orduniq = weboeordd.ORDUNIQ } into weboeorddGroup
from wOEODG in weboeorddGroup.DefaultIfEmpty()
join weboeordsubmit in db2.WebOEOrdSubmit on wOEODG.ORDUNIQ equals weboeordsubmit.ORDUNIQ into weboeordsubmitGroup
from wOEOSG in weboeordsubmitGroup.DefaultIfEmpty()
join webloginaccess in db2.WebLoginAccess on "brian" equals webloginaccess.USER into webloginaccessGroup
from wLAG in webloginaccessGroup.DefaultIfEmpty()
join arcus in db2.Arcus on wLAG.CUSTID equals arcus.IDCUST into arcusGroup
from aG in arcusGroup
where (item.ALLOWINBC == "Yes" && item.ALLOWINAB == "Yes")
&& (item.BASEDESCRIPTION.Contains("dude") || item.DESCRIPTION.Contains("dude") || item.CATEGORY.Contains("dude") || item.FOODACCSPEC.Contains("dude") || item.ITEMBRAND.Contains("dude") || item.ITEMGROUP.Contains("dude") || item.ITEMNO.Contains("dude") || item.ITEMSUBTYPE.Contains("dude") || item.ITEMTYPE.Contains("dude") || iIG.INFO.Contains("dude") || item.UPC.Contains("dude") || item.UPC.Substring(2, 10).Contains("dude"))
&& (iG.CURRENCY == "CDN" && iG.DPRICETYPE == 1)
&& wOEODG.ORDUNIQ != wOEODHG.ORDUNIQ
&& iG.PRICELIST == aG.PRICLIST
orderby item.BASEDESCRIPTION
select new { item.ITEMNO, item.BASEDESCRIPTION, iIG.INFO, item.UPC, iG.UNITPRICE, item.CASEQTY, wOEODG.QTY } into x
group x by new { x.ITEMNO, x.BASEDESCRIPTION, x.INFO, x.UPC, x.UNITPRICE, x.CASEQTY, x.QTY } into items
select items;

要获得与此 SQL 查询相同的结果：

DECLARE @search varchar(50) = 'dude'

SELECT orderformdump.itemno,basedescription,info,upc,CAST(UNITPRICE AS DECIMAL(18,2)),caseqty, sum(qty) AS userquantity
FROM PPPLTD.[dbo].[ORDERFORMDUMP] 
LEFT JOIN PPPLTD.dbo.ICPRICP ON replace(PPPLTD.[dbo].[ORDERFORMDUMP].[ITEMNO],'-','') = ICPRICP.ITEMNO
LEFT JOIN PPPLTD.dbo.WEBITEMINFO ON ORDERFORMDUMP.ITEMNO = WEBITEMINFO.ITEMNO
LEFT JOIN pppltd.dbo.weboeordh ON [user] = 'brian'
LEFT JOIN pppltd.dbo.weboeordd ON pppltd.dbo.WEBOEORDD.ITEMNO = REPLACE(pppltd.dbo.ORDERFORMDUMP.ITEMNO,'-','') and weboeordd.ORDUNIQ = weboeordh.orduniq
Left JOIN pppltd.dbo.weboeordsubmit ON weboeordsubmit.orduniq = weboeordd.ORDUNIQ and weboeordd.ORDUNIQ != weboeordsubmit.orduniq
LEFT JOIN PPPLTD.dbo.WEBLOGINACCESS ON WEBLOGINACCESS.[USER] = 'brian'
LEFT JOIN PPPLTD.dbo.ARCUS ON ARCUS.IDCUST = WEBLOGINACCESS.CUSTID
where (allowinbc = 'Yes' or allowinab = 'Yes') 
AND [PRICELIST] = ARCUS.PRICLIST 
and [CURRENCY] = 'CDN' and DPRICETYPE = 1
and (itemgroup like '%' + @search + '%' or itemtype like '%' + @search + '%' or itembrand like '%' + @search + '%' 
or subcat  like '%' + @search + '%' or orderformdump.description  like '%' + @search + '%' or basedescription like '%'+ @search + '%' 
or orderformdump.ITEMNO like '%'+@search+'%' or UPC like '%'+@search+'%' or (select top 1 1 from pppltd.dbo.ICITEMO where OPTFIELD like 'UPC%' and VALUE like '%'+@search+'%' 
and ITEMNO = pppltd.dbo.ORDERFORMDUMP.itemno) is not null) 
group by ORDERFORMDUMP.ITEMNO,BASEDESCRIPTION,info,UPC,CAST(UNITPRICE AS DECIMAL(18,2)),caseqty
order by basedescription

当我在 LINQPad 上执行 LINQ 时，它会生成以下 SQL：

DECLARE @p0 NVarChar(1000) = '-'
DECLARE @p1 NVarChar(1000) = ''
DECLARE @p2 VarChar(1000) = 'brian'
DECLARE @p3 NVarChar(1000) = '-'
DECLARE @p4 NVarChar(1000) = ''
DECLARE @p5 VarChar(1000) = 'brian'
DECLARE @p6 VarChar(1000) = 'Yes'
DECLARE @p7 VarChar(1000) = 'Yes'
DECLARE @p8 VarChar(1000) = '%dude%'
DECLARE @p9 VarChar(1000) = '%dude%'
DECLARE @p10 VarChar(1000) = '%dude%'
DECLARE @p11 VarChar(1000) = '%dude%'
DECLARE @p12 VarChar(1000) = '%dude%'
DECLARE @p13 VarChar(1000) = '%dude%'
DECLARE @p14 VarChar(1000) = '%dude%'
DECLARE @p15 VarChar(1000) = '%dude%'
DECLARE @p16 VarChar(1000) = '%dude%'
DECLARE @p17 VarChar(1000) = '%dude%'
DECLARE @p18 VarChar(1000) = '%dude%'
DECLARE @p19 Int = 2
DECLARE @p20 Int = 10
DECLARE @p21 VarChar(1000) = '%dude%'
DECLARE @p22 VarChar(1000) = 'CDN'
DECLARE @p23 Int = 1
-- EndRegion
SELECT [t10].[ITEMNO], [t10].[BASEDESCRIPTION], [t10].[value] AS [INFO], [t10].[UPC], [t10].[value2] AS [UNITPRICE], [t10].[CASEQTY], [t10].[value3] AS [QTY]
FROM (
    SELECT [t9].[ITEMNO], [t9].[BASEDESCRIPTION], [t9].[value], [t9].[UPC], [t9].[value2], [t9].[CASEQTY], [t9].[value3]
    FROM (
        SELECT [t0].[ITEMNO], [t0].[BASEDESCRIPTION], [t2].[INFO] AS [value], [t0].[UPC], [t1].[UNITPRICE] AS [value2], [t0].[CASEQTY], [t5].[QTY] AS [value3], [t0].[ALLOWINBC], [t0].[ALLOWINAB], [t0].[DESCRIPTION], [t0].[CATEGORY], [t0].[FOODACCSPEC], [t0].[ITEMBRAND], [t0].[ITEMGROUP], [t0].[ITEMSUBTYPE], [t0].[ITEMTYPE], [t1].[CURRENCY], [t1].[DPRICETYPE], [t5].[ORDUNIQ], [t4].[ORDUNIQ] AS [ORDUNIQ2], [t1].[PRICELIST], [t8].[PRICLIST]
        FROM [ORDERFORMDUMP] AS [t0]
        LEFT OUTER JOIN [ICPRICP] AS [t1] ON REPLACE([t0].[ITEMNO], @p0, @p1) = [t1].[ITEMNO]
        LEFT OUTER JOIN [WEBITEMINFO] AS [t2] ON [t0].[ITEMNO] = [t2].[ITEMNO]
        LEFT OUTER JOIN (
            SELECT [t3].[ORDUNIQ]
            FROM [WEBOEORDH] AS [t3]
            WHERE @p2 = [t3].[USER]
            ) AS [t4] ON 1=1 
        LEFT OUTER JOIN [WEBOEORDD] AS [t5] ON (REPLACE([t0].[ITEMNO], @p3, @p4) = [t5].[ITEMNO]) AND ([t4].[ORDUNIQ] = [t5].[ORDUNIQ])
        LEFT OUTER JOIN (
            SELECT [t6].[CUSTID]
            FROM [WEBLOGINACCESS] AS [t6]
            WHERE @p5 = [t6].[USER]
            ) AS [t7] ON 1=1 
        LEFT OUTER JOIN [ARCUS] AS [t8] ON [t7].[CUSTID] = [t8].[IDCUST]
        ) AS [t9]
    WHERE ([t9].[ALLOWINBC] = @p6) AND ([t9].[ALLOWINAB] = @p7) AND (([t9].[BASEDESCRIPTION] LIKE @p8) OR ([t9].[DESCRIPTION] LIKE @p9) OR ([t9].[CATEGORY] LIKE @p10) OR ([t9].[FOODACCSPEC] LIKE @p11) OR ([t9].[ITEMBRAND] LIKE @p12) OR ([t9].[ITEMGROUP] LIKE @p13) OR ([t9].[ITEMNO] LIKE @p14) OR ([t9].[ITEMSUBTYPE] LIKE @p15) OR ([t9].[ITEMTYPE] LIKE @p16) OR ([t9].[value] LIKE @p17) OR ([t9].[UPC] LIKE @p18) OR (SUBSTRING([t9].[UPC], @p19 + 1, @p20) LIKE @p21)) AND ([t9].[CURRENCY] = @p22) AND ([t9].[DPRICETYPE] = @p23) AND ([t9].[ORDUNIQ] <> [t9].[ORDUNIQ2]) AND ([t9].[PRICELIST] = [t9].[PRICLIST])
    GROUP BY [t9].[ITEMNO], [t9].[BASEDESCRIPTION], [t9].[value], [t9].[UPC], [t9].[value2], [t9].[CASEQTY], [t9].[value3]
    ) AS [t10]
ORDER BY [t10].[BASEDESCRIPTION]

更新

根据 HBomb 的回答，我决定创建一个带参数的存储过程，而不是进行多次连接：

CREATE PROCEDURE PRODUCT_PROCEDURE

    @USERID VARCHAR(MAX)
AS
BEGIN

    SELECT distinct datawarehouse.dbo.orderformdump.itemno, basedescription,info,upc,CAST((SELECT [UNITPRICE] FROM PPPLTD.dbo.[ICPRICP] WHERE [ITEMNO] = replace([DataWarehouse].[dbo].[ORDERFORMDUMP].[ITEMNO],'-','') AND [PRICELIST] = (select top 1 priclist from PPPLTD.dbo.ARCUS where IDCUST = (select top 1 CUSTID from PPPLTD.dbo.WEBLOGINACCESS where [USER] = @USERID)) and [CURRENCY] = 'CDN' and DPRICETYPE = 1) AS DECIMAL(18,2))as price,caseqty, qty AS userquantity FROM [DataWarehouse].[dbo].[ORDERFORMDUMP] LEFT JOIN pppltd.dbo.weboeordd ON pppltd.dbo.WEBOEORDD.ITEMNO = REPLACE(datawarehouse.dbo.ORDERFORMDUMP.ITEMNO,'-','') and orduniq not in (select orduniq from pppltd.dbo.weboeordsubmit) and WEBOEORDD.ORDUNIQ in (select orduniq from pppltd.dbo.weboeordh where [user] = @USERID) LEFT JOIN DATAWAREHOUSE.dbo.webiteminfo on webiteminfo.itemno = orderformdump.itemno where (allowinbc = 'Yes' or allowinab = 'Yes') order by BASEDESCRIPTION

END

然后我使用 Entity Framework 的 Database First 方法来添加我的存储过程，它创建了一个新的 DbContext，该方法使用在我的存储过程中设置“USERID”参数的方法：

public partial class DataWarehouseEntities : DbContext
    {
        public DataWarehouseEntities()
            : base("name=DataWarehouseEntities")
        {
        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            throw new UnintentionalCodeFirstException();
        }

        public virtual ObjectResult<PRODUCT_PROCEDURE_Result> PRODUCT_PROCEDURE(string USERID)
        {
            var USERIDParameter = USERID != null ?
                new ObjectParameter("USERID", USERID) :
                new ObjectParameter("USERID", typeof(string));

            return ((IObjectContextAdapter)this).ObjectContext.ExecuteFunction<PRODUCT_PROCEDURE_Result>("PRODUCT_PROCEDURE", USERIDParameter);
        }
    }

我也试过了：

var USERIDParameter = USERID != null ? new SqlParameter("USERID", USERID) : new SqlParameter("USERID", typeof(string));

return ((IObjectContextAdapter)this).ObjectContext.ExecuteStoreQuery<PRODUCT_PROCEDURE‌​_Result>("PRODUCT_PROCEDURE @USERID", USERIDParameter);

最后，我尝试对存储过程的结果运行更简化的 LINQ 查询：

var products = db2.PRODUCT_PROCEDURE(username).Where
                        (item => item.basedescription.Contains(searchword) 
                         || item.info.Contains(searchword)
                         || item.itemno.Contains(searchword)
                         || item.itemno.Contains(searchword.Replace("-", ""))
                         || item.upc.Contains(searchword));

但是，现在我收到 NullReferenceException，因为查询没有返回任何结果。

更新 #2

执行存储过程不会导致 NullReferenceException。问题在于 LINQ 查询。

我发现当我只有var products = db2.PRODUCT_PROCEDURE(username).ToList() 时，它会返回结果，但是一旦我尝试在其上添加where 子句，它就会返回null。

解决方案

在 HBomb 的帮助下，我解决了这个问题。首先，不是在 LINQ 中创建多个连接，或者创建关联和导航属性，而是在数据库中创建视图或存储过程然后使用其结果编写简单的 LINQ 查询要容易得多（如何做的示例以上）。

我发现我得到了我的 NullReferenceException，因为我的 info 属性的数据库中的某些值为空。为了解决这个问题，我所要做的就是修改存储过程以将info 列更改为isnull(info,'') as info。

最后，为了更好的搜索结果，我更改了查询：

var searchWords = searchword.ToLower().Split(' ');

            var products = db2.PRODUCT_PROCEDURE(username).ToList()
            .Where
                    (item => item.basedescription.ToLower().Contains(searchWords[0])
                     || item.info.ToLower().Contains(searchWords[0])
                     || item.itemno.Contains(searchword)
                     || item.itemno.Contains(searchword.Replace("-", ""))
                     || item.upc.Contains(searchword)
                     || (item.price.ToString() == searchword
                     && item.price.ToString() != null));

            if (searchWords.Length > 1)
            {
                for (int x = 0; x < searchWords.Length-1; x++)
                {
                    products = products.Where(i => i.basedescription.ToLower().Contains(searchWords[x]) || i.info.ToLower().Contains(searchWords[x]));
                }
            }

谢谢。

Answer 1

如果将 Sql 包装在存储过程中，则可以只使用 EF 来调用该过程。这是一种方法：

 var searchParameter = new SqlParameter("@search", mySearchValue);
    this.Database.SqlQuery<YourEntityTypeForReturnVal>("MyProcedureName, @search", searchParameter);

您可以创建参数化存储过程作为 Sql 的包装器：

CREATE PROCEDURE MyProcedureName
    @search varchar(50)
AS
BEGIN
-- Copy and paste your existing Sql Query here, minus the variable declaration

END

有时，作为开发人员，我们能做的最好（也是最难）的事情就是退后一步，问“应该我应该这样做吗”，而不是问“如何 em> 我要这样做吗？”

Answer 2

我会在战斗结束后到达，但这是 QueryFirst 的工作吗？您可以按原样将 SQL 粘贴到查询模板中，但它会保留在您的应用程序中（更易于源代码控制、版本控制、维护）。生成的类使其可以直接从您的应用程序代码中使用。