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可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I have a large data table. There are 10 million records in this table. What is the best way for this query Delete LargeTable where readTime < dateadd(MONTH,-7,GETDATE()) 回答1: If you are Deleting All the rows in that table the simplest option is to Truncate table, something like TRUNCATE TABLE LargeTable GO Truncate table will simply empty the table, you cannot use WHERE clause to limit the rows being deleted and no triggers will be fired. On the other hand if you are deleting more than 80-90 Percent of the data, say if you have total of 11

线性表Linear List 线性表：线性表（Linear List） 是由n（n≥0）个数据元素（结点）a[0]，a[1]，a[2]…，a[n-1]组成的有限序列 其中： 数据元素的个数n定义为表的长度 = "list".length() （"list".length() = 0(表里没有一个元素）时称为空表） 将非空的线性表（n>=0）记作： （a[0]，a[1]，a[2]，…，a[n-1]） 数据元素a[i]（0≤i≤n-1）只是个抽象符号，其具体含义在不同情况下可以不同 线性表的顺序存储结构 //线性表的顺序存储结构 typedef struct{ int *elem; //存储空间基址，即线性表的起始位置，elem指向int的指针 int length; //当前长度 int listsize; //当前分配的存储容量 }SqList; 线性表的顺序表示和实现 线性表的顺序表示指的是一组地址连续的存储单元依次存储线性表的数据元素。 线性表的顺序存储结构是一种随机存储的存储结构。 因为内存中的地址空间是线性的，因此，用物理上的相邻实现数据元素之间的逻辑相邻关系是既简单，又自然的。 由于数组类型也有随机存储的特性，因此通常用数组来描述数据结构中的顺序存储结构。 由于线性表的长度可变，且所需最大存储空间随问题不同而不同，则在C语言中可用动态分配的一维数组。 线性表的起始位置

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: If one call session.save(customerObject) then there is no insert into customer… query into the database. Hibernate will set the id property ("sequence" or "Increment" generator) and bind the entity to a persistence context. The persistence context is synchronized with the database when transaction.commit() is called . Q: where will Hibernate set the id property? Q: will the persistence context cache the sql query insert into customer… before synchronized with db ? I mean,when does sql generated(while doing save or session.flush/tx.commit)

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I am tryng to write a subquery in where clause like below. But i am getting "Correlated column is not allowed in a non-equality predicate:" SELECT *, holidays FROM ( SELECT *, s.holidays, s.entity FROM transit_t tt WHERE ( SELECT Count(thedate) AS holidays FROM fact_ent_rt WHERE entity=tt.awborigin AND ( Substring(thedate,1,10)) BETWEEN (Substring(awbpickupdate,1,10)) AND ( Substring(deliverydate,1,10)) AND ( nholidayflag = true OR weekendflag = true))) s Any issues with this query. because i thought spark >2.0 supported subqueries in where

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 由 翻译 强力驱动 问题: I am using CONTEXT_INFO to pass a username to a delete trigger for the purposes of an audit/history table. I'm trying to understand the scope of CONTEXT_INFO and if I am creating a potential race condition. Each of my database tables has a stored proc to handle deletes. The delete stored proc takes userId as an parameter, and sets CONTEXT_INFO to the userId. My delete trigger then grabs the CONTEXT_INFO and uses that to update an audit table that indicates who deleted the row(s). The question is, if two deletes sprocs from

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I have read somewhere here that using prepared statements in PDO makes your app only immune to first order SQL injections, but not totally immune to second order injections. My question is: if we used prepared statements in all queries inlcuding SELECT queries and not only in INSERT query, then how can a second order sql injection be possible? For example in the following queries there is no chance for a 2nd order injection: write: INSERT INTO posts (userID,text,date) VALUES(?,?,?) read: SELECT * FROM posts WEHRE userID=? delete: DELETE FROM

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I need to create an event inside a procedure, I read somewhere that it's possible but I don't know the syntax. I'm trying: CREATE PROCEDURE DUMMY_PROCEDURE() BEGIN CREATE event e on schedule every 1 second DO INSERT INTO test.t values (current_timestamp); END; But it throws: Any ideas on how to do this?, thanks for reading. '#1576 - Recursion of EVENT DDL statements is forbidden when body is present Edit1: The reason I want to create an event within an event procedure is because it acts as an expiration date, so the function is executed an

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I am using switch table sometime on SQL Server 2008 to transfer quickly data between 2 tables, but I do not know how it works, and what's the difference between this an just a insert into T2 select * from T1 . Someone can explain in detail how it works and the difference? Furthermore I notice that if both tables are not clones this statement does not work. For example if I have one index in one table and not in the other one it fails. 回答1: Inserting data using the statement insert into T2 select * from T1 Loads data by inserting data from T1

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: This is in reference to: byte[] and efficiently passing by reference And the SqlDataReader found in this post: Getting binary data using SqlDataReader Inside a loop, I'm calling a database and returning a large object ( varbinary[max] ). Currently, I'm running into OutOfMemory exceptions, so I'm trying to reduce the footprint in the Large Object Heap (LOH). So, I'm creating a byte array for the largest file that I'd download and adding some padding just in case. For instance: byte[] currentFile = new byte[largestFileSize * 1.1]; I then pass

select * from Student select * from Class select * from Score select * from Subject -- 1、查询出和张三住在同一个地方的学生信息 select * from Student where StuAddress = ( select StuAddress from Student where StuName = ‘ 张三 ‘ ) -- 2、查询年龄大于李四的学生信息 select * from Student where StuAge > ( select StuAge from Student where StuName = ‘ 李四 ‘ ) -- 3、查询和张三在同一个班级的学生信息 select * from Student where ClassID = ( select ClassID from Student where StuName = ‘ 张三 ‘ ) -- 4、查询出所有脱产班的学生信息 select * from Student where ClassID in ( select ClassID from Class where ClassType = ‘ 脱产 ‘ ) -- 5、查询出没有参加过任何考试的学生信息 select * from Student where