SQL Server databases and database brief overview of (a)
A Database (DATABASE)
In accordance with the data structure to organize, store, warehouse management data, is a collection of related data stored together
advantage:
① reduce data redundancy and save data storage space
② with high scalability and ease of data independence
③ achieve full sharing of data resources
II. Database system (DataBase System, referred to as DBS)
Database technology is the use of computer systems, is a database (the data), database management systems (software), database administrators (personnel), hardware platform (hardware) and software platforms (software) run entity composed of five parts. In which the database administrator (DataBase Administrator, referred to as DBA) is a database for planning, design, maintenance and surveillance of professional management, plays a very important role in the database system.
III. Common Object Database
(1) Table
Table is a database that contains all the data in the database object, is the most important SQL Server database logical objects. It consists of rows and columns for organizing and storing data.
(2) field
Each column in the table is called a field, the field has its own properties, such as field types, field size, field type is a field where the most important property which determines which field data can be stored.
SQL specification supports five basic field types: character, type text, numeric, date and time Logical type.
(3) Index
It is a single index, the physical database structure. It is dependent on the table created in the database index the database program without having to scan the entire table, you can find the data in them.
(4) View
Views are derived from one or more tables in the table (also known as virtual table), is the user to view the data in the data table of way. The table includes several rows and columns of data is defined, and data structure built on the basis of a query on the table. Saved view is not data, but the query select list.
(5) stored procedure
Stored procedure (Stored Procedure) is a group in order to accomplish a specific function set of SQL statements (including query, insert, delete, and update operations such), after compiled to store names in the SQL Server server database, the user via the name of the stored procedure to execute. When this stored procedure is invoked to perform these operations will be performed simultaneously.
IV.4 system databases
SQL Server 2012's default installation program will build four system databases (Master, Model, Msdb and Tempdb) during installation. The following were introduced.
(1) master database
SQL Server 2012 master database is the most important database. All system-level information recorded instance of SQL Server, including examples of the scope of the metadata, endpoints, and system configuration settings server links.
(2) tempdb database
tempdb is a temporary database for storing temporary objects or intermediate result sets.
(3) model database
Create an instance of SQL Server is used as the template for all databases. All database changes (such as database size, collation, recovery model, and other database options) to model the database will be used to create the future.
(4) msdb database
Plan for the SQL Server Agent alerts and jobs.
V. history of the development of database technology
1. Artificial management phase
Before the mid-1950s, computer mainly for scientific computing. At that time the hardware and software facilities are very backward, dependent on artificial data base management. Labor management data has the following characteristics:
data is not saved
using application-managed data
data do not share
data are not independent
2. File System stage
The late 1950s to the mid-1960s, hardware and software technology has been further developed, with disks and other storage devices and specialized data management software as a file system, the stage has the following characteristics:
data can be stored for a long
by the file system management data
sharing is poor, large data redundancy
data independence poor
3. Database system stage
Since the late 1960s, used in computer management systems, and the increasing scale, more widely, the rapid growth of the amount of data required for sharing more and more intense, so use the file system management data can not meet requirements, so in order to solve a series of problems, there has been a database system for unified management of data. Emergence of database systems, to meet the multi-user, multi-application needs to share data, has obvious advantages over the file system, marking a leap of data management technology.
