September October 30, 2014 ----- basic knowledge of SQL, September 2014 ----- SQL

September October 30, 2014 ----- basic knowledge of SQL, September 2014 ----- SQL

Database concept

Structured query language: structured query language Abbreviation: SQL

Database management system: database management system (DBMS)

Database Administrator: database administration for short: DBA

SQL language category

DDL Data Definition Language create (create) drop (delete) alter (modify)

DML data operation language CRUD (add, delete, modify, and query)

DCL Data Control Language grant back

SQL server2008 Mode

1. Client/Server (c/s)

2. Browser/Server (B/S)

Database Files

A database can contain up to 32767 data files and 32767 log files.

The main file mdf is used to store data. The startup information must be available and there is only one

The secondary file NDF is used to store data that has not been stored on the primary file.

The log file ldf must be used to record operation information, and at least one

 

One file or file group can only be used for one database, and cannot be used for multiple databases

A file can only be a member of a file group. It cannot be a member of multiple file groups.

A log file cannot be a member of a file group.

Data and log information cannot be stored in the same file or file group.

 

Database System Model:

Link: relation model

Level: hierarchical model

Mesh: network model

 

Operations on relational databases: Select (where) projection (column) join (ROW)

 

 

Database System server type

1. Database Engine: a core service, a complex system, responsible for data storage, processing, and security

2. Analysis service: analyzes and mines data and supports local multi-dimensional data engines. Applications on disconnected clients can browse stored multi-dimensional data locally.

3. reporting service: A Report Server Management Tool

4. Intergration service: responsible for data extraction, reprinting, loading, and other operations. It can efficiently process various data sources, such as Oracle, Excel, and XML documents.

5. SQL server compact edition: not part of SQL server 2008. He is a powerful lightweight relational database engine.

Database products

Oracle, IBM DB2, informix, and Sybase ASE

Microsoft access, Microsoft SQL server, and MySQL open source database

 

System Database

System Database	Type	Purpose	Physical name
	Master	Saves system-level information to control the operation of user databases and database management systems	Master. mdf Mastlog. ldf
	Tempdb	Save all Temporary Information and recreate it to the original value at each startup.	Tempdb. ldf Templog. ldf
	Model	Template database. The first part of the new database is created by copying the content in the model.	Model. mdf Modellog. ldf
	Msdb	A Database Management System proxy program that stores scheduling, alarms, jobs, and other information.	Msdbdata. mdf Msdblog. ldf

 

Unit conversion

1B (byte) = 8b (BIT), B, KB, MB, GB, and TB all multiply by the 10th power of 2

The basic unit of computer operations is B.

The notebook is divided into 32-bit (4-byte) and 64-bit (8-byte) systems, representing the ability to process data.

 

Image bitmap and vector graph

A bitmap is spliced by many points. A single point indicates the size of a pixel.

A vector chart consists of lines. The more you zoom in, the more you zoom in.

Data storage units of SQL server 2008

1> page, the most basic unit

8 KB is one page, 128 page is 1 MB, starting with 96 B Header

The number of data bytes per row in the table cannot exceed 8192-96B (8192 = 1024*8)

2> zone: basic unit for space management

The eight connection pages are one area, that is, 64 KB is one area, and 16 areas are one MB.

Control the storage of tables and indexes. A hybrid disk exists in the case of <64 KB, and the storage is only available in the case of 64 KB.

Name Daquan girl born at December 10, October 30, 2014

Name must read:
I. Output eight characters, analyze the fate of death, and determine that God is the basis for naming. (What is the use of God? God is the five line that plays the most important role in the strong and weak balance of the daily work, also known as the life lord and the Yuan God. It plays a complementary role in helping the life lord. Identifying and using God to help them become weak will play a crucial role in the entire life cycle. If you use God's wrong answer, it will not only help people, but the consequences will be even more serious. It can be said that it will hurt people's life ).
2. The day, place, and person-to-person configuration of the name should be pleasant, but avoid mutual access.
For example, the three talents are not well configured: they have a bad impact on basic operation and success, as well as on the Health and Family of life.
3. No matter what the name is, the five numbers in the name must be avoided. In the five grids, personality is the dominant factor, and the Gex implies that before the middle age, the total Gex affects the life fortune after the middle age. This three Ge is the most important. And pay attention to the difference between men and women.
4. the word and the five lines of the name should be consistent with the word and the word of the Word of the word to remedy the shortcomings of the first destiny, that is, the eight characters ).
5. the font of a name must be opened in a beautiful way to avoid being too heavy.
6. The words in the name should be elegant, and names that are too vulgar, crazy, and too foreign should not be used.
7. The font should be positive, and the length and strength of the text should be matched with the congenital eight characters.
8. The words of the name imply that the name should be used to avoid evil. The words "death", "death", "Father", "child", "weak illness", and "Poverty" must not be used.
 
Pig's luck went to new work units in October 30, 2014

Hello! Your luck is as follows: there will be a hint of breakthrough progress in the face of love. Do not take your inexplicable self-esteem too seriously in a single love affair. Sometimes, female may wish to express each other a little bit and invite them directly when talking. In the past two days, your initiative will not give a bad impression to the other party, but make people feel comfortable and easy to get along with each other. Couples should also pay more attention to the time left for each other. They also take the initiative to propose invitations and enjoy a warm and sweet appointment.