Question

我目前正在使用Entity Framework，需要定期更新大量实体。

我需要做的是添加一个基于几个不同表的日记编号。使用SQL Server，我可以使用存储过程，内部和外部联接，GROUP BY和ROW_NUMBER，这对我来说非常重要，也非常有效。

请参阅以下过程代码：

CREATE PROCEDURE [dbo].[sp_UpdateNumber]
    @RefId int
AS
BEGIN
    UPDATE TableWithNumber 
    SET Nmr = other.Nmr
    FROM (
        SELECT MIN(C.Nmr) as Nmr, Z_ID
        FROM
        (
            SELECT 
                ROW_NUMBER() OVER (ORDER BY D.TicksCreatedOn, D.Z_Id, D.B_ID) as Nmr, D.*
                FROM (
                    SELECT 
                            S.Id as S_ID,
                            Z.Id as Z_ID,
                            B.Id as B_ID,
                            S.TicksCreatedOn
                    FROM 
                            ChildTable as B
                            INNER JOIN TableWithNumber Z on Z.ChildTableRefA_Id = B.Id
                            INNER JOIN ParentTable S on Z.ParentTable_Id = S.Id
                    WHERE S.Ref_Id = @RefId
                UNION
                    SELECT 
                            S.Id as S_ID,
                            Z.Id as Z_ID,
                            B.Id as B_ID,
                            S.TicksCreatedOn
                    FROM 
                            ChildTable as B
                            INNER JOIN TableWithNumber Z on Z.ChildTableRefB_Id = B.Id
                            INNER JOIN ParentTable S on Z.ParentTable_Id = S.Id
                    WHERE S.Ref_Id = @RefId) as D
        ) as C
    GROUP BY C.Z_ID) as other
    WHERE other.Z_ID = Id AND Ref_Id = @RefId
END

由于SQL Ce中没有可用的存储过程，以及如何在子选择中使用GROUP BY的进一步限制，我现在必须计算代码中的日记数。我在Context上使用SqlQuery来检索所需的最小数据集，对其进行分组，然后开始每个实体的更新。

SELECT ZID
FROM
    (SELECT S.Id as [SID], Z.Id as [ZID], B.Id as [BID], S.TicksCreatedOn
    FROM ChildTable AS B
        INNER JOIN TableWithNumber as Z on Z.ChildTableRefA_Id = B.Id
        INNER JOIN ParentTable as S on Z.ParentTable_Id = S.Id
    WHERE S.Ref_Id = @RefId
    UNION
    SELECT S.Id as [SID], Z.Id as [ZID], B.Id as [BID], S.TicksCreatedOn
    FROM ChildTable AS B
        INNER JOIN TableWithNumber as Z on Z.ChildTableRefB_Id = B.Id
        INNER JOIN ParentTable as S on Z.ParentTable_Id = S.Id
        WHERE S.Ref_Id = @RefId) AS D
ORDER BY TicksCreatedOn, ZID, BID


        var result = Database.SqlQuery<NumberUpdate>(QUERY, new SqlCeParameter("@RefId", 1)).ToList();

应用程序上的代码看起来有点像

    var grouped = result
        .Select((x,y) => new NumberUpdate { ZID = x.ZID, Number = ++y })
        .GroupBy(x => x.ZID);

    foreach (var group in grouped)
    {
        Database.ExecuteSqlCommand("UPDATE TableWithNumber SET Number = @Nr WHERE Id = @Id",
            new SqlCeParameter("@Nr", group.Min(x => x.Number)),
            new SqlCeParameter("@Id", group.Key));
    }

我想知道在SQL CE中更新实体列表是否比在foreach循环中调用ExecuteSqlCommand更快或更有效？

Answer 1

如果您的业务逻辑允许您“逐行”更新多个表中的数据（不是使用复杂的SQL命令），您可以尝试“表直接”方法。它涉及以下步骤。

使用指向SDF文件的连接字符串创建 SqlCeConnection 对象。使用命令类型 CommandType.TableDirect 为此连接创建 SqlCeCommand 对象。使用选项 ResultSetOptions.Updatable 和 ResultSetOptions.Scrollable 创建 SqlCeResultSet 。

现在，您可以使用 Seek ， Read 和 Update 方法更新表行。这种方法可能是最快的方法。但它需要编写比传统EF方法更多的代码。

SQL Compact Edition批量更新

1 个答案: