SQL Server

From the top-down query method, query out itself and all descendant data:--as(Selectfromwhere ID= Select fromwhere t.parentid=m.id)Select from Maco ORDER BY ID DescFrom the bottom up query, query out itself and all the direct

First, the database login Server name:. Contact this machine Authentication: Windows Authentication (Administrator rights) and SQL Server Authentication Login name: SA (default login name) II. Database Conventions The

1. Declaration and use of variablesDECLARE @var as varchar (50)Set var= ' ABCD '2. If loopIf IsNull (@prjid, 0) =0Beginprint ' did not find prjid!!! ‘ReturnEndElseBegin--You must write some code here, otherwise you will get an error.End3, the use of

Operating system: Windows 10 64-bitJava Development environment: MyEclipseDatabase: SQL Server 2012JDBC Driver PackageDownload Sqljdbc4.jarImport into ProjectJava code1 PackageCom.cl.util;2 3 Importjava.sql.Connection;4 ImportJava.sql.DriverManager;

The concept of constraints: Ensure that valid values are entered in the columns and maintain relationships between the tables.Primary key ConstraintFunction: Primary KEY (PRIMARY KEY constraint), one table can only have one, cannot have null value,

I. Download the SQL Server R2 installation fileCn_sql_server_2008_r2_enterprise_x86_x64_ia64_dvd_522233.isoSecond, burning the installation files into a CD-ROM or using a virtual CD-ROM to load, or directly unzip, open the installation files, the

Read Catalogue 1.LEFT (character_expression, integer_expression) 2.RIGHT (character_expression, integer_expression) 3.SUBSTRING (character_expression, start, length) In SQL Server we often need to

Read Catalogue Way 1-round Way 2-cast Rounding in SQL usually has two ways: round and cast (... as decimal ()).The personal advice is to use the cast method:Back to TopWay toroundAfter testing, the same can be rounded, but round

Read Catalogue SQL Server Functions---Union and UNION ALL differences Back to top SQL Server functions---Union and UNION ALL differencesIf we need to display the results of the two SELECT statements as a whole, we need to use the union

Qlserver provides a rich system view, from macro to micro, from static to dynamic response database object storage results, system performance, system wait events and so on. It also retains a view of compatibility with earlier versions, the main

-------Adding constraints, increasing deletions1 UseStudentDB22 Go3 --------Create a student table---------4 Create TableStudentinfo (5 --StudentID int PRIMARY key NOT NULL identity,---set as primary key and self-growing6StudentIDint not NULL

If you want to uninstall SQL Server, uninstall the operating system directly!!!The reasons are as follows: SQL Server is closely related to the operating system and calls the relevant components, which can cause many problems. Clean up the

Before the SQL Server 2008R database was used because of the project requirements, after the installation is complete, you will encounter some problems when you log inThe problem is:When you connect locally, localhost,. etc. cannot log in directly,

Notes for SQL Server Alwayson agent job creation, sqlalwayson Preface Always On availability group activity auxiliary features include support for backup operations On secondary copies. Backup operations may put a lot of pressure on I/O and CPU

SQL Server queries problems by time period, SQL Server queries Baidu's materials are saved as follows: When writing SQL statements that query by time period, we generally write the query conditions as follows: where date>='2010-01-01' and

SQL stored procedure instance-dynamically copies data from one table to another based on table data. Dynamically copy data from one table to another based on the table data Copy the records in the track table to the corresponding track _? Table

SQL Server float uncertainty Most of the time, we all know that the floating point storage is an uncertain value, and you will never know whether it is something like 0 = 0.00000000000000123 or 0 = 0.00000000000999. There may be no problems at the

Analysis of insufficient System tablespace alarms and analysis of system table alarms The Code is as follows: -- After logging on to an alert with insufficient SYSTEM tablespace, the SYSTEM finds that sys. aud $ occupies too many places. SQL> select

SqlServer uses a common table expression (CTE) to build an infinite tree structure. sqlservercte Starting from SQL Server 2005, we can use CTE to support recursive queries. CTE is the common table expression. A common table expression (CTE) is a

Sqlserver: Query lock SQL statements and Unlock methods. sqlserversql View locked table statements -- View the locked table: SELECTrequest_session_id spid, OBJECT_NAME (resource_associated_entity_id) tableNameFROMsys. dm_tran_locksWHEREresource_type