SQL database-<1>sql language

relational database, SQL language simple, learning software introduction

sql:structured Query Language structured querying language

The database is divided into: hierarchical type, net type, relational type.

Relational database: A collection of two-dimensional tables that can be used to store different types of data information
Commonly used databases include: Oracle/mysql/microsoft SQL server/access/db2/postgresql, etc. .....

Transact-SQL language
is a SQL language developed by Microsoft that is based on the Sybase database and the database communication language in the Microsoft SQL Server database.

Classification of SQL languages: ddl/dql/dml/dcl/transaction Control Language
Note: DDL: Data Definition language
DQL: Data Query Language
DML: Data Manipulation language (add, delete, change, check)
DCL: Data Control Language

Basic software used in this Learning database: SQL Server (SQL Server Management Studio)

Note: Install the software, familiar with the basic operation of the software

Several elements of data logging:
1. Server type--database engine
2. Server name--native. or (local), remote computer name or IP
3. Authentication--windows authentication (administrator use), SQL Server Authentication (developer)
4. User name: SA-Super admin
5. Password: How to set

Two ways to sign in: Windows identity logon; SQL Server identity login. (can distinguish between the two types of login in the nature of different)
How do I set up SQL Server authentication?
1. Object Explorer Right-click-Properties--Security--sqlserver and Windows identity login.
2. Object Explorer--security--Login--sa--Right click--Properties--general--Set password
3. Object Explorer--security--Login--sa--Right click--Properties--state--grant, enable
Restart the database service. (Multiple ways to restart the service)

Three-tier structure of the database:
1.. mdf in the Data folder of the hard drive. Where the data is stored.
2.SqlServer of service.
3. Database Management interface

Database file Composition:
Three kinds: main file (. MDF), secondary data files (. ndf), log files (. LDF);
In a database, you can have multiple log files, multiple secondary data files, but only one master data file.

SQL database-<1>sql language