Shulou(Shulou.com)06/01 Report--

1. The concept of database:

Popularly speaking, it is the place where data is hoarded and stored, not limited to disks, hard disks, floppy disks and other places where power is not easy to lose, but also can be used for data hoarding.

Official definition: a warehouse that organizes, stores, and manages data according to the data structure.

Early storage: the earliest use is the hole of the punch card, and the light bulb is turned off to represent the data input and output.

Later, the data was saved on magnetic tape, but the tape can only be read and written sequentially, not random access. IBM invented the disk drive in 1956 to support random access. With the advent of the information age, there are a large number of data to be stored and managed, and the database management system DBMS was born.

two。 Classification of databases

Classified according to database model: hierarchical database, mesh database, relational database.

2.1 hierarchical database:

A tree structure is used to represent entities and their relationships. Relationships only support one-to-many, representing the database IBM IMS.

IBM also has a DB2 database of representative products, paid products. It is a relational database.

2.2 mesh database:

The database developed by General Electric, founded by Edison, can only run on GE's own mainframe.

Nodes store data and use node relationships to describe the relationship between data. Many-to-many relationships can be supported.

2.3 Relational databases: (current mainstream databases)

Using a two-dimensional table composed of rows and columns to organize data and relationships, rows can describe both data entities and relationships between entities.

Compared with the network and hierarchical database, the relational database is simpler, and the relational database is supported by strict mathematical theory. (researcher E.F.Codd)

The structured data system based on relational model is called RDBMS

Mainstream relational databases: Oracle's Oracle and Mysql Microsoft's Ms SQL's former infomix, Sybase, etc.

Mysql:

MySQL 4.0supports MyISAM, and InnoDB Mysql 5.0is called milestone version.

MySQL's engine is plug-in and can support many kinds of engines:

MyISASM, does not support transactions, insert and query fast.

InnoDB, supports transactions, row-level locks, and mysql5.5 becomes the default engine

Go to IOE:

It is a concept coined by Alibaba. The original intention is to remove IBM minicomputers, Oracle databases and EMC storage devices from Alibaba's IT architecture and replace them with systems developed on the basis of open source software.

4.NoSQL: a general term for non-SQL and non-traditional relational databases. It was born in 1998 and was proposed again in 2009 as a non-relational, distributed database design pattern that does not provide transactional ACID. (for example: Sina blog, dealing with a large number of comments and so on)

5. Popular database heat meter and part introduction:

Popularity database ranking of data intercepted by a website

1.SQLite: relational database management system, is a lightweight database, designed for application in embedded products.

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