Oracle from entry to mastery (4th Edition)

1. summary

Oracle Database 19c stay 2019 Released in , As Oacle Database12c and 18c Long term supported versions of the series , It can provide the highest 
 Level version stability and the longest support service and error repair help .


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 Database technology is to deal with information resources （ That is, a large amount of data ） Management requirements of . Data management technology has experienced manual management 、 file system 、 Database system 3 Stages .

 Database models mainly include hierarchical models 、 Mesh model and relational model .

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 A relational database is a database based on a relational model , With the help of set algebra and other mathematical concepts and methods to deal with the data in the database .

 The relational model describes data in a two-dimensional table . In a relational model , Each table has multiple field columns and record rows .

 In a relational model , Relation is a two-dimensional table composed of rows and columns , The rows in the table are called Yuanzu , The columns in the table are called attributes . It can uniquely identify the differences in the table 
 Attributes or attribute groups of rows （ That is, the combination of multiple attributes ） It is called primary key or conforming primary key .

2. Database design paradigm

 The normalized database must conform to the normal form rules of the relational model .



 First normal form (1NF)