如何在Dapper中使用一个sql语句传递多个记录进行更新

Question

我试图使用一个单独的Update语句来更新具有不同值的多个记录(我不是要尝试更新许多行以具有相同的值,这非常简单).这就是我现在正在尝试的:

    using (var cn = GetOpenConnection()) {

        // get items where we need to set calculated fields that will now be persisted in the DB
        var items = cn.Query<MaintenanceItem>("select TOP 500 * from [Maintenance] where Tolerance IS NOT NULL");

        foreach (var mi in maintItems)
        {
            // Set calculated fields on multiple recrods
            logic.CalculateToleranceFields(mi, true);
        }


        var updateInput = items.Select(a => new {a.ToleranceMonths, a.ToleranceDays, a.ToleranceHours, a.ToleranceLandings, a.ToleranceCycles, a.ToleranceRIN }).ToList();

       // THIS DOESN'T WORK - attempting to update multiple rows with different values
       var numResults = cn.Execute(@"UPDATE rm 
                SET rm.ToleranceMonths=ur.ToleranceMonths, 
                rm.ToleranceDays=ur.ToleranceDays, 
                rm.ToleranceHours=ur.ToleranceHours, 
                rm.ToleranceLandings=ur.ToleranceLandings, 
                rm.ToleranceCycles=ur.ToleranceCycles, 
                rm.ToleranceRIN=ur.ToleranceRIN 
            from [RoutineItems] rm
            Inner Join @UpdatedRecords ur ON rm.AircraftId=ur.AircraftId AND rm.ItemNumber=ur.ItemNumber", updateInput);

        Assert.IsTrue(numResults == maintItems.Count());

    }

Dapper可以进行这种批量更新吗？我宁愿大量更新,而不是使用for循环将数据推送到数据库中.

Answer 1

看起来目前在Dapper中只有一个语句是不可能的.在考虑为实现这一目标而需要做些什么时,这是完全可以理解的.

我最终做的是使用3个语句来创建临时表,填充需要更新的数据,然后使用内部联接调用更新到临时表:

cn.Execute(@"create table #routineUpdatedRecords
                        (
                            AircraftId int, 
                            ItemNumber int,
                            ToleranceMonths int,
                            ToleranceDays int,
                            ToleranceLandings int,
                            ToleranceCycles decimal(12,2),
                            ToleranceRIN decimal(12,2),
                            ToleranceHours decimal(12,2)
                        );");


cn.Execute(@"Insert INTO #routineUpdatedRecords 
    VALUES(@AircraftId, @ItemNumber, @ToleranceMonths, @ToleranceDays, 
@ToleranceLandings, @ToleranceCycles, @ToleranceRIN, @ToleranceHours)", updateInput);

var numResults = cn.Execute(@"UPDATE rm 
                                SET rm.ToleranceMonths=ur.ToleranceMonths, 
                                rm.ToleranceDays=ur.ToleranceDays, 
                                rm.ToleranceHours=ur.ToleranceHours, 
                                rm.ToleranceLandings=ur.ToleranceLandings, 
                                rm.ToleranceCycles=ur.ToleranceCycles, 
                                rm.ToleranceRIN=ur.ToleranceRIN 
                            from [RoutineItems] rm
                            Inner Join #routineUpdatedRecords ur ON rm.AircraftId=ur.AircraftId AND rm.ItemNumber=ur.ItemNumber");

我相信这比在循环中调用update更快,因为我正在更新大约600K行.