<> One ,SQL Server Basic introduction

<>1.1, summary

SQL Server yes Microsoft Relational database management system launched by the company . It has the advantages of easy to use, good scalability and high degree of integration with related software , Straddle slave operation Microsoft
Windows 98 Laptop to run Microsoft Windows 2012 Large multiprocessor servers and other platforms .
Microsoft SQL Server Is a comprehensive database platform , Use integrated business intelligence (BI) Tools provide enterprise level data management .Microsoft SQL
Server Database engine provides more secure and reliable storage function for relational data and structured data , Enables you to build and manage highly available and high-performance data applications for your business .

<>1.2, Application scope

SQL Server Application scope of , It has a certain relationship with its specific version , Basically : Enterprise Edition (Enterprise Edition)
( Business of large and medium-sized enterprises ); Standard Edition (Standard Edition) ( Small business ); Development version (Developer Edition)
( development company , Used by developers ); Personal Edition (Personal Edition) ( Used by developers );MSDE 2000(Microsoft SQL Server
2000 Desktop Engine)( Simple stand-alone database , Developer development test use )

<>1.3, Advantages and disadvantages

(1) Strong expansibility : When the system needs higher database processing speed , Simply add a database server Can be extended .
(2) Maintainability : When a node fails , The system will automatically detect the failure and transfer the application of the failed node , Ensure the continuous work of database .
(3)
Security : Because the data will be synchronized on multiple servers , Data set redundancy can be realized , Security through multiple data . In addition, it successfully put the database into the intranet , Better protection of database security .
(4) Ease of use : Completely transparent to applications , What the cluster exposed is a IP
shortcoming :
Ⅰ. Can't follow Web The processing power of the server distributes the load .
Ⅱ. Load Balancer ( Control end ) fault , The whole database system will be paralyzed .

<>1.4, Basic grammar

increase :insert into Target data sheet select * from Source data table " ( Add records from the source data table to the target data table )

Delete :delete from data sheet where Conditional expression

change :update data sheet set field 1= value 1, field 2= value 2 …… field n= value n where Conditional expression

check :select * from data sheet where Field name = field value order by Field name [desc]

<> Two ,MySQL Basic introduction

<>2.1, summary

MySQL Is a relational database management system , By Sweden MySQL AB Company development , Currently belongs to Oracle Subsidiaries .MySQL The most popular relational database management system , stay
WEB Application MySQL It's the best RDBMS (Relational Database Management System, Relational database management system )
One of application software .MySQL
It is an associated database management system , Associated database saves data in different tables , Instead of putting all the data in one big warehouse , This increases speed and flexibility .MySQL Used SQL
Language is the most commonly used standardized language for accessing database .

<>2.2, Application scope

Web Website system : Simple installation and configuration , Superior performance , Open Source .

Log management system : Efficient insertion and query capabilities , If the design is better , in use MyISAM When storing the engine , The two can not lock each other , Achieve high concurrent performance .

Data warehouse system : In the need of large storage space and efficient data analysis , At present, there are basically three ways to solve this problem :1, Using expensive high performance hosts to improve computing performance , Improve with high-end storage devices I/O performance , Ideal effect , But the cost is very high ;2, Low cost by copying data to multiple hard disks with large capacity pcserver upper , To improve overall computing performance and I/O ability , Good effect , Storage space is limited , Low cost ;,3, By splitting data horizontally , Use multiple cheap ones pcserver And local disks to store data , Every machine has only a part of all the data , Solve the problem of data volume , All pcserver Parallel computing together , It also solves the problem of computing power , Allocate the operation tasks of each machine through the intermediate agent , It can solve both computing performance problems and problems I/O Performance issues , It's also cheap . For the second and third ,MySQL All have great advantages ( Simple replication across domains , Free Admission ).

Embedded system : The biggest limitation of embedded environment to software system is the limited hardware resources , Software system running in embedded environment , Must be lightweight and low consumption software .MySQL There are versions specifically for embedded systems .

<>2.3, Advantages and disadvantages

1, support 5000 Data warehouse of 10000 records ;2, Suitable for all platforms ;3, Open source software , Quick version update ;4, Excellent performance . Purely in terms of performance ,MySQL It's pretty good , Because it contains a default desktop format MyISAM.MyISAM
The database is very compatible with the disk and does not take up too much CPU And memory .MySQL Can run on Windows System without conflict , stay UNIX Or similar UNIX It is better to run on the system . You can use the 64 Bit processor for additional performance . because MySQL It's used inside a lot of times 64 Integer processing of bits ;5, cheapness

shortcoming :
Lack of functions of some stored programs , Unfamiliar keywords are not supported , Use default port IP( It's also an advantage ), Vulnerable to hackers .MyISAM(MySQL Default storage engine for , The other is innoDB) Transaction not supported .

<>2.4, Basic grammar

MySQL The basic syntax and SQL Server Basically the same .

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