Review of MySQL (I): go deep into MySQL

MySq Review ( One )： thorough MySql

How to be in Windows Window login Mysql？

If in cmd Windows cannot log in Mysql, Remember to Mysql Of bin The path is added to the... Of the environment variable Path Directory ！！！

 Do not want the password to be seen ：
mysql -uroot -p
Enter password：******

stop it Mysql：net stop mysql

start-up Mysql：net start mysql

How to modify Mysql password ？

• Method 1 ：

• Method 2 ：

  

• Method 3 ：

  

• Method four ：

  

Sql、DB、DBMS The relationship between ？

• DB:
  DataBase( database , The database actually exists on the hard disk in the form of files )
• DBMS :
  DataBase Management System ( Database management system , Common are : MySQL Oracle DB2 sybase SqlServer…)
• SQL:
  Structured query language , It's a standard universal language . The standard sql Suitable for all database products .
  SQL When a statement is executed , In fact, the internal will compile first , And then execute sql.(sql language Sentence compilation by BMS complete .)
  DBMS Responsible for the execution of sql sentence , Through execution sq1l Statement to operate DB The data .
  DBMS - ( perform )-> SQL - ( operation )-> DB

What is a watch ？

surface ：table

Is the basic component of the database , All the data is organized in the form of tables , The purpose is to be readable .

A table includes rows and columns ：

​ That's ok ： It's called data / Record （data）

​ Column ： It's called a field （column)

Student number	full name	Age
110	Zhang San	20
120	Li Si	21

Sql The classification of sentences

• DQL： Data query language data query languge

  Query statement , Anyone who seclect sentence , All are DQL.

• DML： Data operation language data manage languge

  insert、delete、update , Add, delete and modify the data in the table ..

• DDL： Data definition language data definition languge

  create、drop、alter, Modification of table structure .

• TCL： Transaction control language Transaction control languge

  commit Commit transaction ,rollback Roll back the transaction .

• DCL： Data control language data control languge

  grant to grant authorization ,revoke Revocation of authority, etc .

Import data

Baidu network disk link ：https://pan.baidu.com/s/1Pgnb1fwNbC-VaFfFC-5xOg

Extraction code ：8b2y

1. land MySql database

2. See what databases are

   show databases; This is not sql sentence , yes Mysql The command statement of .

3. Create your own database

   create database bjpowernode;

4. Use your own database

   use bipowernode;

5. See which tables are in the database you are currently using

   show tables;

6. Initialization data

   source D:\LeStoreDownload\Msq note \bjpowernode.sql

View table structure

desc Table name ;

• Department information sheet ：dept

English field name	Chinese description	type
DEPTNO	Department number	INT(2)
DNAME	Department name	VARCHAR(14)
LOC	Location	VARCHAR(13)

• Employee information form ：emp

English field name	Chinese description	type
EMPNO	Employee number	INT (4)
ENAME	Employee name	VARCHAR(10)
JOB	jobs	VARCHAR(9)
MGR	Superior leaders	INT (4)
HIREDATE	Date of entry	DATE
SAL	salary	DOUBLE(7,2)
COMM	allowance	DOUBLE (7,2)
DEPTNO	Department number	INT(2)

Be careful ：DEPTNO Field is a foreign key ,DEPTNO Value from dept Primary Key , It acts as a constraint

• Salary grade information table ：saldrade

English field name	Chinese description	type
GRADE	Grade	INT
LOSAL	Minimum salary	INT
HISAL	The highest salary	INT

English field name	Chinese description	type
GRADE	Grade	INT
LOSAL	Minimum salary	INT
HISAL	The highest salary	INT