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

RDBMS (Relational Database Management System) Relational Database:

The structure of relational database:

Row: OK, record, also known as record

Column: column, field, property, or field

Primary key: primary key, which must be assigned and unique, used to uniquely determine a field of a record, such as a student number (unique keys can be empty or multiple)

Domain:the range or domain of value, for example, male and female, age 0-150

Transaction: multiple operations are treated as a whole. Either finish it or don't do it. In other words, affairs must be an indivisible whole, just like the atoms we learned in chemistry, the atoms are the smallest units that make up matter.

ACID:

A:atomicity

C:Consistency

I:Isolation

D:Durability

Entity-Relation: entity-relation model

Entity is represented by a rectangular box in the eMurr diagram.

Relation, job number and position in the employee table

Contact type

1:1

1:n

M:n

The foreign key table of the third table (foreign key) and other primary key tables are used to form multiple many-to-one relations to solve the many-to-many relationship.

Regularization analysis

Paradigm NF

First, there are no duplicate columns, there cannot be multiple values in the same column, and an attribute in an entity cannot have multiple values or duplicate attributes.

Second, each column in the table is related to the primary key. It cannot be related to only one part of the primary key (mainly for federated primary keys). That is to say, in a database table, only one kind of data can be saved in a table, and multiple data can not be saved in the same database table.

Third, ensure that each column is directly related to the primary key column, not indirectly, and the third paradigm needs to ensure that each column of data in the data table is directly related to the primary key, not indirectly.

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