用实体框架执行自定义sql？

Question

我需要执行一个自定义查询,它将保存在数据库的某个地方,我需要它返回数据表或数据集并将其绑定到gridview,它将自动生成列为true.

我的所有数据访问层都与实体框架完美配合,但对于某些特定场景,我需要这样做,我想知道是否应该将ado.net与实体框架结合起来,或者如果EF能以某种方式实现它

Answer 1

对于Entity Framework 5使用

context.Database.SqlQuery

对于Entity Framework 4,请使用以下代码

context.ExecuteStoreQuery

 public string BuyerSequenceNumberMax(int buyerId)
    {
        string sequenceMaxQuery = "SELECT TOP(1) btitosal.BuyerSequenceNumber FROM BuyerTakenItemToSale btitosal " +
                                  "WHERE btitosal.BuyerID =  " + buyerId +
                                  "ORDER BY  CONVERT(INT,SUBSTRING(btitosal.BuyerSequenceNumber,7, LEN(btitosal.BuyerSequenceNumber))) DESC";

        var sequenceQueryResult = context.Database.SqlQuery<string>(sequenceMaxQuery).FirstOrDefault();

        string buyerSequenceNumber = string.Empty;

        if (sequenceQueryResult != null)
        {
            buyerSequenceNumber = sequenceQueryResult.ToString();
        }

        return buyerSequenceNumber;
    }

对于Return a List,请使用以下代码

 public List<PanelSerialList> PanelSerialByLocationAndStock(string locationCode, byte storeLocation, string itemCategory, string itemCapacity, byte agreementType, string packageCode)
 {
       string panelSerialByLocationAndStockQuery = "SELECT isws.ItemSerialNo,  im.ItemModel " +
        "FROM Inv_ItemMaster im   " +
        "INNER JOIN  " +
        "Inv_ItemStockWithSerialNoByLocation isws  " +
        "   ON im.ItemCode = isws.ItemCode   " +
        "       WHERE isws.LocationCode = '" + locationCode + "' AND  " +
        "   isws.StoreLocation = " + storeLocation + " AND  " +
        "   isws.IsAvailableInStore = 1 AND " +
        "   im.ItemCapacity = '" + itemCapacity + "' AND " +
        "   isws.ItemSerialNo NOT IN ( " +
        "           Select sp.PanelSerialNo From Special_SpecialPackagePriceForResale sp  " +
        "           Where sp.PackageCode = '" + packageCode + "' )";



    context.Database.SqlQuery<PanelSerialList>(panelSerialByLocationAndStockQuery).ToList();


}

Answer 2

这是另一个维度和更简单的方法.使用您的实体框架获取SQL连接上下文:

var connection = (System.Data.SqlClient.SqlConnection) _db.Database.Connection;

if (connection != null && connection.State == ConnectionState.Closed)
{
    connection.Open();
}

var dt = new DataTable();

using (var com = new System.Data.SqlClient.SqlDataAdapter("Select * from Table", connection))
{
    com.Fill(dt);
}

我们可以使用DataAdapter或任何其他经典方法使用EF连接执行查询.

当我们动态地执行某些操作以及无法映射到实体时,这将非常有用.例如,我们可以在DataTable中获取内容.

上面的语法适用于EF 5.0.

Answer 3

如果您的目标是返回ADO.NET结构(DataTable或DataSet),那么只需使用经典的ADO.NET.您会发现比尝试将数据绑定到实体集然后自己填充DataTable或DataSet更容易.

但是,如果您真的真的有兴趣通过EntityFramework运行自定义查询,请查看ExecuteQuery.它允许您执行SQL查询并将结果映射回模型中的实体.然后,您将获取IEnumerable结果并将其映射到DataTable或DataSet.因此,我原来的回答是"只需用优质的ADO.NET方法做到这一点."