本文转自:http://www.cnblogs.com/gudujianxiao/archive/2012/07/17/2594709.html SSIS Data Flow 中有几个组件可以实现不同数据源的数据合并功能,比如 Merger, Merge Join 和 Union All.它们的功能比较类似,同时也比较容易混淆,下面是对它们之间的区别的对比总结. 下面通过三个 Data Flow 来演示这三个组件的使用以及相关的配置. 测试数据源 - 第一个数据源是一张表 USE BIWORK_
Merge, join, and concatenate pandas provides various facilities for easily combining together Series, DataFrame, and Panel objects with various kinds of set logic for the indexes and relational algebra functionality in the case of join / merge-type o
1.Split SQL Server 2008 新语法: DECLARE @str VARCHAR(MAX) SET @str = REPLACE(@teeIDs, ',', '''),(''') SET @str = 'SELECT * FROM (VALUES(''' + @str + ''')) AS V(A)' EXEC (@str) 据说这个SQL语法是SQL Server 2008的. SELECT * FROM (VALUES(1),(2),(3)) AS V(A) 配合个临
应用这边新上线了一个查询,正在跑,让我看下状态以及分析下能不能再快点. 如下sql: SELECT x.order_no , order_date+7/24 AS order_date, address || district AS ADDRESS, city , extn_style_number || '-' || extn_color_number , SUM(line_total) , SUM(ORDERED_QTY) , CASE WHEN division='55' THEN 'SW
一些联合表查询语句,这些表里都建立有索引.在没有加 option ( force order ) 前,整个查询费时40多秒,但 单独表 查询基本不到1秒.查看查询计划后发现查询过程是从table n开始使用索引与 table s 等匹配,再与table m中的b匹配,导致整个查询最多表的扫描次数上千次多,逻辑读上万次.加了 option ( force order ) 后,最多表查询扫描次数在10次以内,逻辑读最多的也就千出头.整个查询费时不到1秒,CPU运行占用时间599MS.分享一下. 以下
原文链接:关于oracle with as用法 with as语法–针对一个别名with tmp as (select * from tb_name) –针对多个别名with tmp as (select * from tb_name), tmp2 as (select * from tb_name2), tmp3 as (select * from tb_name3), … 1 2 3 4 5 6 7 8 9 --相当于建了个e临时表 with e as (select * f