Question

我想知道你们推荐什么是从Sql Server中的MERGE语句获取动作计数的最佳方法。

所以，即我运行一个MERGE，它执行一些插入，一些更新和一些删除，...我希望能够找到HOW MANY插入，HOW MANY更新和多少删除。

最好的方法是什么？

Answer 1

您可以在MERGE语句中指定OUTPUT子句，并获取MERGE期间已完成的输出报告。

MERGE (targetTable) AS t 
USING (sourceTable) AS s
ON t.ID = s.ID
WHEN MATCHED THEN
  (some statements)
WHEN NOT MATCHED THEN
  (some statements)
OUTPUT
  $action, inserted.ID 'inserted', deleted.ID 'deleted'
;

这将为每个操作的每个“操作”（插入，更新，删除）提供一行。如果它是很多语句，你也可以输出到@tableVar然后查看表变量。

DECLARE @tableVar TABLE (MergeAction VARCHAR(20), InsertedID INT, DeletedID INT)

MERGE (targetTable) AS t 
USING (sourceTable) AS s
ON t.ID = s.ID
WHEN MATCHED THEN
      (some statements)
WHEN NOT MATCHED THEN
      (some statements)
OUTPUT
      $action, inserted.ID 'inserted', deleted.ID 'deleted' INTO @tableVar
;

SELECT MergeAction, COUNT(*) 
FROM @tableVar  
GROUP BY MergeAction

查看联机丛书，了解有关MERGE声明和OUTPUT clause的详细信息。

马克

Answer 2

要提取到单个变量，可以使用pivot：

通过marc_s发布流程答案

    declare
        @mergeResultsTable table (MergeAction VARCHAR(20));

    declare
        @insertCount int,
        @updateCount int,
        @deleteCount int;

    merge ...
    output $action into @mergeResultsTable; 

    select @insertCount = [INSERT],
           @updateCount = [UPDATE],
           @deleteCount = [DELETE]
      from (select 'NOOP' MergeAction -- row for null merge into null
             union all
            select * from @mergeResultsTable) mergeResultsPlusEmptyRow     
     pivot (count(MergeAction) 
       for MergeAction in ([INSERT],[UPDATE],[DELETE])) 
        as mergeResultsPivot;

如果init vars为0或者知道源表或目标表有> 0行，则可以删除union'nop'行。

Answer 3

怎么样：

INSERT YourResultsTable (action, cnt)
SELECT action, count(*)
FROM
(
    MERGE (targetTable) AS t 
    USING (sourceTable) AS s
       ON t.ID = s.ID
    WHEN MATCHED THEN      (some statements)
    WHEN NOT MATCHED THEN      (some statements)
    OUTPUT $action as action, inserted.ID as ins, deleted.ID as del
) m
GROUP BY action;

[编辑]好的，请尝试：

INSERT YourResultsTable (action)
SELECT action
FROM
(
    MERGE (targetTable) AS t 
    USING (sourceTable) AS s
       ON t.ID = s.ID
    WHEN MATCHED THEN      (some statements)
    WHEN NOT MATCHED THEN      (some statements)
    OUTPUT $action as action, inserted.ID as ins, deleted.ID as del
) m;

（然后计算结果）

罗布

Sql Server 2008 MERGE - 获取计数的最佳方式

3 个答案: