Question

我通过以下方式从数据库获取数据：

curl -X PUT http://127.0.0.1:9200/test_file \   -d '{   "settings": {
    "analysis": {
      "filter": {
        "autocomplete_filter": {
          "type": "edge_ngram",
          "min_gram": 3,
          "max_gram": 20
        },
        "custom_ascii_folding": {
          "type": "asciifolding",
          "preserve_original": true
        }
      },
      "analyzer": {
        "autocomplete": {
          "type": "custom",
          "tokenizer": "standard",
          "filter": [
            "lowercase",
            "autocomplete_filter",
            "snowball",
            "custom_ascii_folding"
          ]
        }
      }
    }   },   "mappings": {
    "sample": {
      "properties": {
        "id": {
          "type": "keyword"
        },
        "title": {
          "type": "text",
          "term_vector": "yes",
          "analyzer": "autocomplete"
        }
      }
    }   } }'

curl -X PUT http://127.0.0.1:9200/test_file/sample/1 -d '{"id": "1","title": "Four Beautyful Sun Flower - Episode 01"}' 
curl -X PUT http://127.0.0.1:9200/test_file/sample/2 -d '{"id": "2","title": "Four Beautyful Sun Flower - Episode 15"}' 
curl -X PUT http://127.0.0.1:9200/test_file/sample/3 -d '{"id": "3","title": "Four Beautyful Sun Flower - Episode 17"}' 
curl -X PUT http://127.0.0.1:9200/test_file/sample/4 -d '{"id": "4","title": "Four Beautyful Sun Flower - Episode 23"}' 
curl -X PUT http://127.0.0.1:9200/test_file/sample/5 -d '{"id": "5","title": "Sun Flower In Morning - Episode 01"}' 
curl -X PUT http://127.0.0.1:9200/test_file/sample/6 -d '{"id": "6","title": "Sun Flower In Morning - Episode 15"}' 
curl -X PUT http://127.0.0.1:9200/test_file/sample/7 -d '{"id": "7","title": "Sun Flower In Morning - Episode 17"}' 
curl -X PUT http://127.0.0.1:9200/test_file/sample/8 -d '{"id": "8","title": "Sun Flower In Morning - Episode 23"}'

现在，我尝试使用sql查询来实现这一目标：

 result = (from d in context.FTDocuments
                          join f in context.FTDocFlags on d.ID equals f.DocID into fgrp
                          from x in fgrp.DefaultIfEmpty()
                          where d.LevelID == levelID && x.UserID == userID && d.Status.Equals(DocumentStatus.NEW)
                          select new Entities.Document
                          {
                              ArrivalDate = d.ArrivalDate.Value,
                              BundleReference = d.BundleRef,
                              CreatedDate = d.CreatedDate,
                              CustomerID = d.CustomerID,
                              DocType = d.DocType.Value,
                              GuidID = d.DocGuid,
                              ID = d.ID,
                              LastExportID = d.LastExpID,
                              LevelID = d.LevelID,
                              ProfileID = d.ProfileID,
                              ScanDate = d.ScanDate.Value,
                              ScanOperator = d.ScanOperator,
                              SenderEmail = d.SenderEmail,
                              Status = d.Status,
                              VerifyOperator = d.VerOperator,
                              FlagNo = x == null ? 0 : x.FlagNo,
                              FlagUserID = x == null ? 0 : x.UserID
                          }).ToList();

但是得到以下错误：

数据阅读器有多个字段。多个字段对EDM原语或枚举类型无效

是否可以使用上述复杂查询？

我使用EF 6.0。

Answer 1

your query does not return a single string. Use like:

var test = context.Database.SqlQuery<Entities.Document>("...");

Answer 2

试试这个

const string query = @"select *from FTDocument d left outer join FTDocFlag f on d.ID=f.DocID";

var test = context.Database.SqlQuery<Entity>(query).ToList();

Answer 3

在我的回答中，我首先假设了 EntitityFramework（ObjectContext），但之后我又添加了 DbContext 的代码。

要查看下面的示例，您可以使用LinqPad并使用 EntitityFramework（ObjectContext）通过添加连接添加您的Entity Framework DLL。指定连接属性并关闭连接对话框。然后选择连接并运行示例：

void Main()
{
    var context=this; // requires that you selected an EF ObjectContext connection  
    var q=context.ExecuteStoreQuery<FTDocument>(
                                   "SELECT * FROM FTDocument WHERE ID = @p0", 1);
    q.ToList().Dump();
}

它将接受所有类型的SQL查询，您可以使用@p0，@p1等参数，并在调用函数ExecuteStoreQuery时简单地将它们以逗号分隔。结果将以List<FTDocument>的形式返回。要将其转换为List<string>，您需要指定要返回的数据库字段 - 或者在每行中创建以逗号分隔的字段值列表，例如：

    q.Select(s=>s.ID+", "+s.GuidID+", "+s.DocType).ToList().Dump();

同样的例子，但这次使用的是 EntityFramework（DbContext）：

使用 EntitityFramework（DbContext V4 / V5 / V6）通过添加连接添加实体框架DLL。指定连接属性（不要忘记指定AppConfig文件）并关闭连接对话框。然后选择连接并运行示例：

void Main()
{
    var context=this; // requires that you selected an EF DBContext (V4/5/6) connection 
    var q=context.Database.SqlQuery<FTDocument>(
                               "SELECT * FROM FTDocument WHERE ID = @p0", 1);
    q.ToList().Dump();
}

提示：在关闭连接对话框之前，请单击测试。如果您知道连接成功，它将在以后让您头疼。对于所有想要使用不同的EF项目和自己的数据库进行尝试的人，here is快速教程如何创建它。然后，只需将上面示例中的FTDocument替换为您选择的另一个表（在SQL字符串中，当然在括号<...>内）。

在EF中使用sql查询

3 个答案: