SQL Server的隐藏特性

SQL Server有哪些隐藏特性?

例如，没有文档的系统存储过程，做一些非常有用但没有足够文档的事情的技巧?

答案

感谢大家的精彩回答!

存储过程

sp_msforeachtable: Runs a command with '?' replaced with each table name (v6.5 and up) sp_msforeachdb: Runs a command with '?' replaced with each database name (v7 and up) sp_who2: just like sp_who, but with a lot more info for troubleshooting blocks (v7 and up) sp_helptext: If you want the code of a stored procedure, view & UDF sp_tables: return a list of all tables and views of database in scope. sp_stored_procedures: return a list of all stored procedures xp_sscanf: Reads data from the string into the argument locations specified by each format argument. xp_fixeddrives:: Find the fixed drive with largest free space sp_help: If you want to know the table structure, indexes and constraints of a table. Also views and UDFs. Shortcut is Alt+F1

片段

Returning rows in random order All database User Objects by Last Modified Date Return Date Only Find records which date falls somewhere inside the current week. Find records which date occurred last week. Returns the date for the beginning of the current week. Returns the date for the beginning of last week. See the text of a procedure that has been deployed to a server Drop all connections to the database Table Checksum Row Checksum Drop all the procedures in a database Re-map the login Ids correctly after restore Call Stored Procedures from an INSERT statement Find Procedures By Keyword Drop all the procedures in a database Query the transaction log for a database programmatically.

功能

哈希字节（） EncryptByKey 枢轴命令

Misc

Connection String extras TableDiff.exe Triggers for Logon Events (New in Service Pack 2) Boosting performance with persisted-computed-columns (pcc). DEFAULT_SCHEMA setting in sys.database_principles Forced Parameterization Vardecimal Storage Format Figuring out the most popular queries in seconds Scalable Shared Databases Table/Stored Procedure Filter feature in SQL Management Studio Trace flags Number after a GO repeats the batch Security using schemas Encryption using built in encryption functions, views and base tables with triggers

当前回答

Vardecimal存储格式

SQL Server 2005为数字和十进制数据类型添加了一种新的存储格式，称为vardecimal。Vardecimal是十进制类型的一种变长表示，可以在行的每个实例中保存未使用的字节。如果十进制定义很大(如decimal(38,6))，但存储的值很小(如0.0)，或者有大量重复值，或者数据填充稀疏，则可以节省最多的时间。

Link

2008-09-29 17:02:46

其他回答

行构造函数

您可以用一个插入语句插入多行数据。

INSERT INTO Colors (id, Color)
VALUES (1, 'Red'),
       (2, 'Blue'),
       (3, 'Green'),
       (4, 'Yellow')

2009-12-18 19:39:27

我不确定这是否是一个隐藏的功能，但我偶然发现了这个功能，并发现它在很多情况下都很有用。您可以在单个选择语句中连接一组字段，而不是使用游标并遍历选择语句。

例子:

DECLARE @nvcConcatonated nvarchar(max)
SET @nvcConcatonated = ''

SELECT @nvcConcatonated = @nvcConcatonated + C.CompanyName + ', '
FROM tblCompany C
WHERE C.CompanyID IN (1,2,3)

SELECT @nvcConcatonated

结果:

Acme, Microsoft, Apple,

2009-05-21 18:10:32

@Gatekiller -一个更简单的方法来获得日期肯定是

CAST(CONVERT(varchar,getdate(),103) as datetime)

如果在本地不使用DD/MM/YYYY，则需要使用与103不同的值。SQL Books Online中的查找转换函数用于区域代码。

2008-09-26 17:18:55

有时没有合适的列来排序，或者您只是想要表上的默认排序顺序，并且希望枚举每一行。为了做到这一点，你可以把“(select 1)”放在“order by”子句中，你就会得到你想要的东西。整洁的,是吗?

select row_number() over (order by (select 1)), * from dbo.Table as t

2010-09-05 15:37:31

SQL Server 2005:

select * from sys.dm_os_performance_counters

select * from sys.dm_exec_requests

2008-09-23 16:05:02

SQL Server的隐藏特性

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