问题描述
好的，我刚刚从我之前的问题中意识到这一点:根据辅助表中的行更新主表
Ok I just realized that from my previous question: Update main table based on rows from a secondary table
那是如何使用辅助表更新主表的计数，但由于此查询将在 sql 作业中，我如何删除我刚刚计算的行，并确保我不删除任何新的行插入辅助表?
That was how to update the main table with the count using the secondary table, but since this query will be in a sql job, how can I delete the rows I just counted, and making sure I don't delete any new rows inserted into the secondary table?
推荐答案
如果我没看错，您想(在您的第一个问题中)使用与每个 EmployeeID 关联的唯一 IP 数更新 SelectionCount，现在在同一过程中，从 Selection 表中清除构成这些计数的记录 - 同时不触及自 SelectionCount 更新以来添加的任何记录.如果您的选择表具有 1) 主键和 2) 行的创建日期，这将容易得多.两者的缺失使事情变得复杂.
If I'm reading it right, you want to (in your first question) update the SelectionCount with the number of unique IPs associated with each EmployeeID, and now in the same process clear out the records from the Selection table that made up those count - while simultaneously not touching any records added since the SelectionCount was updated. This would be a lot easier if your selection table had 1) a primary key, and 2) a date the row was created. The absence of both complicates things.
因此，我们将采用一种稍微奇怪的方式(假设您无法更改架构).这假设您使用的是 SQL 2005 或 2008 :
So we'll do this a slightly odd way (assuming you're not able to change your schema). This assumes you're using SQL 2005 or 2008 :
我在这里猜测你的数据类型
I'm guessing your datatypes here
DECLARE @TempIPs TABLE(EmployeeID int, ipaddress varchar(25))
DELETE FROM Selection
OUTPUT deleted.EmployeeID, deleted.ipAddress
INTO @TempIPs
--用保存旧 IP 的 @TempIPs 替换对选择表的引用.
--replace reference to Selection table with @TempIPs which holds the legacy IPs.
UPDATE Employee
SET SelectionCount = IsNull((SELECT Count(DISTINCT ipAddress)
FROM @TempIPs
WHERE @TempIPs.EmployeeID = Employee.ID), 0)
如果您计划在添加新记录时继续增加 SelectionCount，只需将 + SelectionCount 添加到您的 UPDATE 语句中.您还应该将整个批次包装在交易 (BEGIN TRANSACTION....COMMIT TRANSACTION) 语句中.
If you're planning to keep increasing the SelectionCount as new records are added, just add + SelectionCount to your UPDATE statement. You should also wrap the whole lot inside a transaction (BEGIN TRANSACTION....COMMIT TRANSACTION) statement.
这篇关于如何将计数的行标记为已删除?续上一个问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持编程学习网！