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

仅限返回日期

Select Cast(Floor(Cast(Getdate() As Float))As Datetime)

Select DateAdd(Day, 0, DateDiff(Day, 0, Getdate()))

2008-09-23 15:54:23

其他回答

dm_db_index_usage_stats

这允许您知道表中的数据最近是否更新过，即使表上没有DateUpdated列。

SELECT OBJECT_NAME(OBJECT_ID) AS DatabaseName, last_user_update,*
FROM sys.dm_db_index_usage_stats
WHERE database_id = DB_ID( 'MyDatabase')
AND OBJECT_ID=OBJECT_ID('MyTable')

代码来自:http://blog.sqlauthority.com/2009/05/09/sql-server-find-last-date-time-updated-for-any-table/

参考资料: SQL Server -表的最后插入行的日期/时间是什么?

在SQL 2005及更高版本中可用

2010-08-30 15:40:59

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

您可以用子查询创建一个逗号分隔的列表，并且后面没有最后一个逗号。据说这比之前使用的函数更有效。我想是2005年之后。

SELECT 
    Project.ProjectName,
    (SELECT
        SUBSTRING(
            (SELECT ', ' + Site.SiteName
            FROM Site
            WHERE Site.ProjectKey = Project.ProjectKey
            ORDER BY Project.ProjectName
    FOR XML PATH('')),2,200000)) AS CSV 
FROM Project

您还可以使用带有嵌套查询的FOR XML PATH来选择XML，我发现这很有用。

2011-11-09 19:54:42

SQL Server 2005:

select * from sys.dm_os_performance_counters

select * from sys.dm_exec_requests

2008-09-23 16:05:02

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

SQL Server的隐藏特性

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