Question

我有这个查询，其结果实现了IEnumerable。

RoutesEntities routesModel = new RoutesEntities();
LocalesEntities localesModel = new LocalesEntities();

var routesQuery = from rs in routesModel.Routes.ToList()
                  join ls in localesModel.Locales.ToList() 
                  on rs.LocaleID equals ls.LocaleID
                  select new
                  {
                      LocaleID = rs.LocaleID,
                      RouteName = rs.RouteName
                  };

问题：如何从此查询中生成SQL，或如何将其类型转换为ObjectQuery以使用routesQuery.ToTraceString()？有可能吗？

原因：我想将所有SQL查询记录到DB，但我不想为连接的上下文（表）创建新对象

重要：我最初无法使用ObjectQuery因为我毕竟使用了

ListView.DataSource = routesQuery;
ListView.DataBind()

它可能导致在一个数据源上使用不同的上下文（DB表）时出错。

那么我该怎么做才能生成SQL查询？

提前致谢。

Answer 1

var routesQuery = from rs in routesModel.Routes.ToList() 
                  join ls in localesModel.Locales.ToList()

设置此查询的方式是，将整个Routes表加载到内存中，并将整个Locales表加载到内存中。您的查询（有两个），看起来像：

select fieldlist
from tablename

您应该将两个查询分成单独的ObjectQuery实例，并单独记录它们。但更重要的是，你可能不应该将未经过滤的表格内容读入内存！

Answer 2

您违反两个不同的数据上下文，因此您将对每个上下文运行不同的查询并将结果加入客户端。对于LINQ-to-SQL上下文，数据库中的查询可以记录为Femaref已经指出的。 EF ObjectContext仍有工作要做，以赶上LINQ-to-SQL并且不提供日志记录。但是ObjectQuery.CommandText会返回查询文本。无法记录客户端中的连接，因为它不存在。它不是SQL查询，是LINQ-to-Objects循环。

Answer 3

有答案：

http://arteinvolo.org.ua/2010/09/21/how-to-use-entity-framework-with-multiple-entities/

public static EntityConnection setSchema(string[] edmxFiles) 
{
            XNamespace edmxns = "http://schemas.microsoft.com/ado/2007/06/edmx";
            XNamespace edmns = "http://schemas.microsoft.com/ado/2006/04/edm";
            XmlDocument edmxXml = new XmlDocument();
            XmlNamespaceManager nameSpace = new XmlNamespaceManager(edmxXml.NameTable);

            List<XmlReader> ssdlReader = new List<XmlReader>();
            List<XmlReader> csdlReader = new List<XmlReader>();
            List<XmlReader> mslReader = new List<XmlReader>();

            foreach (string edmxFile in edmxFiles)
            {
                edmxXml.Load(edmxFile);
                nameSpace.AddNamespace("edmx", edmxns.NamespaceName);

                XmlNode ssdlNode = edmxXml.SelectSingleNode("//edmx:StorageModels", nameSpace);
                XmlNode csdlNode = edmxXml.SelectSingleNode("//edmx:ConceptualModels", nameSpace);
                XmlNode mslNode = edmxXml.SelectSingleNode("//edmx:Mappings", nameSpace);

                ssdlReader.Add(XmlReader.Create(new StringReader(ssdlNode.InnerXml)));
                csdlReader.Add(XmlReader.Create(new StringReader(csdlNode.InnerXml)));
                mslReader.Add(XmlReader.Create(new StringReader(mslNode.InnerXml)));
            }

            StoreItemCollection storageCollection = new StoreItemCollection(ssdlReader);
            EdmItemCollection edmCollection = new EdmItemCollection(csdlReader);
            StorageMappingItemCollection mappingCollection = new StorageMappingItemCollection(edmCollection, storageCollection, mslReader);

            MetadataWorkspace workSpace = new MetadataWorkspace();
            workSpace.RegisterItemCollection(storageCollection);
            workSpace.RegisterItemCollection(edmCollection);
            workSpace.RegisterItemCollection(mappingCollection);

            SqlConnection metaConnect = new SqlConnection(ConfigurationManager.ConnectionStrings["CustomSqlConnection"].ToString());
            EntityConnection entityConnect = new EntityConnection(workSpace, metaConnect);

            return entityConnect;
}

使用方法：

EntityConnection entityConnection = Connector.setSchema(new string[] {
                Path.GetFullPath(AppDomain.CurrentDomain.BaseDirectory + "/App_Model/RoutesModel.edmx"),
                Path.GetFullPath(AppDomain.CurrentDomain.BaseDirectory + "/App_Model/LocalesModel.edmx")
});

entityConnection.Open();
String queryData = "SELECT rs.RouteID, rs.RouteURL, ls.LocaleName, ls.IsActive, ls.LocaleDescription FROM RoutesEntities.Routes AS rs INNER JOIN LocalesEntities.Locales AS ls ON ls.LocaleID = rs.LocaleID";
EntityCommand queryCommand = new EntityCommand(queryData, entityConnection);
DbDataReader routesReader = queryCommand.ExecuteReader(CommandBehavior.SequentialAccess);

ListView.DataSource = routesReader;
ListView.DataBind();

LINQ生成的SQL用于记录

3 个答案: