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This article will explain in detail what you need to master about the introduction to sql database, and the content of the article is of high quality, so the editor will share it with you for reference. I hope you will have a certain understanding of the relevant knowledge after reading this article.

I believe that many beginners are at a loss when they are kicked into the SQL database, saying that they do not know where to start, and it is very difficult to systematically study the SQL database. Here are some of the contents that you need to master when you get started with SQL database.

1. Getting started with SQL database

SQLServer2000 installation, configuration, server start, stop, enterprise manager, query analyzer

Generation database-mesh database and hierarchical database; second generation database-relational database

Database (DB); database management system (DBMS); database system (DBS)

SQLServer2000 is available in different versions: enterprise, Standard, personal, Development

Data type in SQLServer: integer: int,smallint,tinyint,bigint; floating point: real,float,decimal; binary: binary,varbinary; logic: bit; characters: char,nchar,varchar,nvarchar; text and graphics: text,ntext,image; date and time: datetime,smalldatetime; currency: money,smallmoney

Creation and deletion of database; creation, modification and deletion of database tables

Data integrity: entity integrity: PrimaryKey,UniqueKey,UniqueIndex,IdentityColumn; domain integrity: Default,Check,ForeignKey,Datatype,Rule; referential integrity: ForeignKey, Check,Triggers,Procedure; user-defined integrity: all column-level and table-level constraints in Rule,Triggers,Procedure;CreateTable

There are five kinds of constraints in SQLServer: primary key constraint (PrimaryKeyConstraint), default constraint (DefaultConstraint), check constraint (CheckConstraint), sexual constraint (UniqueConstraint), and foreign key constraint (ForeignKeyConstraint).

Relation diagram

Steps of database design: requirement analysis, conceptual structure design, logical structure design, database physical design, database implementation, database operation and maintenance

The connection between two entities: one-to-one (1:1), one-to-many (one-to-many), many-to-many (MRAV)

Entity relation Model-- Emurr Diagram

Database normalization: simplify the structure of the database to the simplest form; remove redundant columns from the table; identify all data that depends on other databases.

Database three paradigms: the normal form is a column without repetition; the second paradigm is that the non-principal attribute is not partially dependent on the primary keyword; the third paradigm is that the attribute does not depend on other non-primary attributes.

2. SQL statement

SQL is "structured query language (StructuredQueryLanguage)"

Four parts of SQL:

Data definition language DDL (DataDefinitionLanguage) is used to define the structure of data: create, alter, drop.

Data control language DCL (DataControlLanguage) is used to control the access permission, access authority and other commands of database components: grant, revoke.

Data manipulation language DML (DataManipulationLanguage) commands used to manipulate data in a database: insert, update, delete.

Data query language DQL (DataQueryLanguage) is a command used to query data in a database: select.

Operators in SQL: arithmetic operator, bit operator, comparison operator, logical operator, wildcard operator, string concatenator, assignment operator

3. Query

Simple query, using the TOP clause

Sort the query results orderby

Conditional query where, using arithmetic expressions, using logical expressions, using the between keyword, using the in keyword.

Simple subquery: nested subquery, related subquery; orderby clause can not be used in the select statement of subquery, roderby clause can only sort the final query results.

Nested subquery: execution process, first execute the subquery, the results of the subquery are not displayed, but passed to the outer query as a condition of the outer query, and then execute the outer query and display the results.

The execution of the nested subquery does not depend on the outer query, and the subquery is executed only once.

Subqueries with comparison operators, subqueries with in and notin, subqueries with any or all

Related subquery: the subquery is executed once for each row of the outer query, which passes the value of the column referenced by the subquery to the subquery.

The execution of related subqueries depends on the outer query, and the subqueries need to be executed repeatedly.

Import and export:

DTS (DataTransformationService) is a data transmission service provided by SQLServer. Enables users to extract, transform, and merge data from completely different data sources into single or multiple purposes.

On the introduction to the sql database need to master what to share here, I hope the above content can be of some help to you, can learn more knowledge. If you think the article is good, you can share it for more people to see.

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