and records

Copyright NOTICE: This article is the original article of Bo Master, reprint annotated source http://blog.csdn.net/u0131427811. Super key, candidate key, primary key, foreign keyHyper-Key: A property set that uniquely identifies a tuple in a

1. Key candidate key for primary key Super keyPrimary key:A combination of data columns or properties in a database table that uniquely and fully identifies the stored data object. A data column can have only one primary key , and the value of the

Fuzzy query likeReplace any character with%Where goods_name like ' Nokia% ';Clear a few characters on the underlineUnderline wildcard single character,% wildcard anyExercisesTurn a bunch of 10, 20, and 30 numbers into 10,20,30.Which is to remove

TRUNCATE table is functionally the same as a DELETE statement without a WHERE clause: Both delete all rows in the table. However, TRUNCATE TABLE is faster than DELETE and uses less system and transaction log resources. The DELETE statement deletes

Same point:1.truncate and delete without a WHERE clause, and drop deletes the data in the table.2.drop, truncate are DDL statements (data definition language) that are automatically committed after execution.Different points:1. Truncate and delete

After the instance has been allocated the memory structure, loads the control file, then wants to open the database, needs to do the control file, the data file, the online redo log maintains the mutual state consistency, the database can open. When

Official English document Original: https://source.android.com/compatibility/cts-intro.htmlCompatibility Test SuiteCompatibility test SuiteHow do does the CTS work?How does the CTS work? Figure 1. How to use CTSFigure 1. CTS usage

This article mainly describes how to deal with UNIX or NT system intrusion.Note: All your steps during system recovery should be consistent with the network security policy of your organization.A. Preparations1. discuss security policiesIf your

Most campus networks have become part of the Internet. The Internet is no longer free to use, making campus network security especially important. Here I will discuss the following issues: ○ Why is the Internet insecure? Network System Security

1. Preface With the rapid development of computer technology, the database has been widely used in various fields, but data security issues have emerged. Security issues of a large amount of data in databases of various application systems, as well

Some unnecessary services are enabled by default in various major linux releases. For Ubuntu, we can use the method of selective shutdown to accelerate startup and improve system performance. Here we install a software:

Author: Lin Yusheng Cao Lei Zhang yaoyun Article Source: Shanghai computer user Association 1. Preface With the rapid development of computer technology, the database has been widely used in various fields, but data security issues have emerged.

Use vswitch network terminology to make your article more professional. Content: Broadcast (Broadcast), BroadcastAddress (Broadcast address), Collision (conflict), FlowControl (Traffic Control ), full-duplex (Full duplex) and so on. Vswitch Network

This article introduces the optimal performance of a vswitch in VLAN application configuration. The content of this article is as follows: filtering service function, Layer 2 network layer switch, Layer 3 network layer switch, data frame inbound,

Mysql bin provides two Commands: mysqldump and resource. Mysql command line to export the database: 1. Run the command to enter the bin directory of the mysql installation directory. For example, run the command cd C: Program FilesMySQLMySQL

In daily work, protecting data from unauthorized users is a special concern of system administrators. If you are currently using MySQL, you can use some convenient functions to protect the system, greatly reducing the risk of unauthorized access to

(1) Differences Between Layer 2 switches, Layer 3 switches, and Layer 4 switches The layer-2 switching technology is mature. The layer-2 switch is a data link layer device that can identify the MAC address information in the data packet and forward

Some concepts required to use Linux-general Linux technology-Linux technology and application information. For more information, see the following. 1) MBR means that the DATA on the hard disk is composed of five parts: MBR, DBR, FAT, DIR, and DATA.

6.1 data access page view test site 1 page view is a way to view the generated data access page style. When you open a data access page in the design view of Test Site 2, you must modify the data access page. Click the name of the data access page

Tag: UTC time TimestampThis article is purely integrated and records the UTC time used in the project and the conversion to. NET timestamps.1, Android get UTC time /*** Get UTC time** @return*/public static String Getutctimestr ()