Operation code for database part knowledge using JAVA

This week, we first temporarily ended the advanced knowledge of java and entered the study of database:

Advanced part of java:
          1. Multi-threading: Thread concurrency (multiple threads operate shared variables) ;
lock mechanism, keywords are synchronize (safety, lock objects and methods), WAIT, notify
(pessimistic) dead lock, wait, notify, notifyall;
2. Network programming: UDP data broadcast (the data sender only needs to send one copy to the switch, and the switch is responsible for making n copies of this information and sending it to all machines)
                                     Http Protocol (HyperText Transfer Protocol)
                           Json data format, syntax rules: JSON Object {"attribute name": "Attribute value"}
json array ["Element 1", "Element 2" ...]
JSON plug-in: -JSON-LIB
- Gson ##- Jackson
- Fastjson -Alibaba
;
database part: (using MySQL5.5 database, and Navicat graphics tools to operate)
3. System and MySQL commonly used command
system commands (with by the Run as administrator)

: #Start service

net start mysql

                                                                                                                                                                                                  ’s ’s ’s ’ s ’ s ’ ‐     ‐   ‐   ‐ ‐‐ ‐‐ net stop mysql


                                                               
mysql -uroot -p password

                                                                                                                                                                  

#                                                                                                                                                                                                                                                             Backup database instance mysqldump -uroot -proot mydb > d:/mydb.sql
                                                                                                                                                                        ’ s ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ d:/mydb.sql to uroot -proot mydb tbuser > d:/tbuser.sql  
                 

Mysql common commands

:-Show the database instance
Show databases;

-Create the database instance
Create database Mydb;

-Display all database tables in the instance
Show Tables;
## SQL statement

# Auto_increment: Set up columns, which can be used for the primary key column and the unique column of non -air (not null unique)

                                                                                                                                                                                                                                                                                       ​​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​When defining the length, add 0 to the front of the value)

, alter, drop

                                                                                                         . Language: control authority) revork, grant;

                5. (Integrity Conditions) Constraints: 1. Primary key constraint
2. Foreign key constraint

3. Not empty constraint

4. Unique constraint
5. Check constraint (mysql does not support it yet)

                                                                                                                                                                                                                                          .         FROM target table


                                                                                                                                                                                                                                     ​ 


【GROUP BY column Name】

## [HAVING Query Conditions]

## 【Order By column name ASC | Desc】

                                                【LIMIT [偏移行,]记录行数】
  
                                              单表查询：模糊查询（“%”，“_”），聚合函数
                                              多表查询：等值连接，外连接
                                              mysql函数的使用。

import java.io.Serializable;

/**
 * 工作详情类
 * @author NIUXUYUAN
 */
public class Jobs implements Serializable{

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	private String id;          //id
	private String experience;  //工作经验
	private String city;        //工作地点
	private String industry;    //行业
	private String detail;      //工作详情
	private String company;     //公司
	private String jobname;     //职位
	public Jobs(String id, String experience, String city, String industry, String detail, String company,
			String jobname) {
		super();
		this.id = id;
		this.experience = experience;
		this.city = city;
		this.industry = industry;
		this.detail = detail;
		this.company = company;
		this.jobname = jobname;
	}
	
	@Override
	public String toString() {
		return "Jobs [id=" + id + ", experience=" + experience + ", city=" + city + ", industry=" + industry
				+ ", detail=" + detail + ", company=" + company + ", jobname=" + jobname + "]";
	}
	
	public String toString(int i) {
		return experience+city+industry+detail+company+jobname;
	}

	public Jobs() {
		// TODO Auto-generated constructor stub
	}

	public String getId() {
		return id;
	}

	public void setId(String id) {
		this.id = id;
	}

	public String getExperience() {
		return experience;
	}

	public void setExperience(String experience) {
		this.experience = experience;
	}

	public String getCity() {
		return city;
	}

	public void setCity(String city) {
		this.city = city;
	}

	public String getIndustry() {
		return industry;
	}

	public void setIndustry(String industry) {
		this.industry = industry;
	}

	public String getDetail() {
		return detail;
	}

	public void setDetail(String detail) {
		this.detail = detail;
	}

	public String getCompany() {
		return company;
	}

	public void setCompany(String company) {
		this.company = company;
	}

	public String getJobname() {
		return jobname;
	}

	public void setJobname(String jobname) {
		this.jobname = jobname;
	}
	
}

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;
import java.util.List;

public class AddJobs {

	static List<Jobs> list = new ArrayList<>();
	File file = new File("jobs");
	
	/**
	 * 输入数据
	 * @throws IOException
	 */
	public void input() throws IOException {
	     BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	     System.out.println("以id/experience/education/city/industry/detail/company/jobname格式填入：");
	     String msg = "";
	     while(!(msg = br.readLine()).equalsIgnoreCase("quit")) {
	    	 add(msg);
	     }
	     br.close();
	}

	/**
	 * 将数据变为Jobs对象存入list集合
	 * @param msg
	 */
	private void add(String msg) {
		String[] s = msg.split("/");
		Jobs job = new Jobs(s[0], s[1], s[2], s[3], s[4], s[5], s[6]);
		list.add(job);
	}
	
	private void checkFile() throws FileNotFoundException, IOException, ClassNotFoundException {
		if(file.length()>0) {
		ObjectInputStream ois = new ObjectInputStream(new FileInputStream(file));
		List<Jobs> temp = (List<Jobs>)ois.readObject();
		if(temp!=null) {
			list.clear();
			for(Jobs t:temp) {
				list.add(t);
			}
		}
		ois.close();
		}
	}
	public static void main(String[] args) throws FileNotFoundException, IOException, ClassNotFoundException {
		AddJobs aj = new AddJobs();
		if(!aj.file.exists()) {
			aj.file.createNewFile();
		}
		aj.checkFile();
		aj.input();
		ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(aj.file));
		oos.writeObject(list);
		oos.close();
	}

}

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.ObjectInputStream;
import java.util.ArrayList;
import java.util.List;

public class Query {

	static List<Jobs> list = new ArrayList<>();
	File file = new File("jobs");

	/**
	 * 查看file文件，将数据导入list集合
	 * @throws FileNotFoundException
	 * @throws IOException
	 * @throws ClassNotFoundException
	 */
	private void checkFile() throws FileNotFoundException, IOException, ClassNotFoundException {
		if(file.length()>0) {
		ObjectInputStream ois = new ObjectInputStream(new FileInputStream(file));
		List<Jobs> temp = (List<Jobs>)ois.readObject();
		if(temp!=null) {
			list.clear();
			for(Jobs t:temp) {
				list.add(t);
			}
		}
		ois.close();
		}
	}
	
	public void check() throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		System.out.println("请输入experience/education/city/industry/detail/company/jobname的某些信息");
		String msg = br.readLine();
		String[] s = msg.split("/");
		String regex = "";
		for (String str : s) {
			regex += "[\\s\\S]*" + str + "[\\s\\S]*";
		}
		List<Jobs> temp = new ArrayList<>();
		for (Jobs j : list) {
			msg = j.toString(1);
			if(msg.matches(regex)) {
				temp.add(j);
			}
		}
		System.out.println("结果");
		for (Jobs jobs : temp) {
			System.out.println(jobs);
		}
	}
	public static void main(String[] args) throws FileNotFoundException, ClassNotFoundException, IOException {
		Query q = new Query();
		q.checkFile();
		q.check();
	}
}

 相关文章：

Java连接MySQL数据库及简单操作代码

数据库基础知识

The above is the detailed content of Operation code for database part knowledge using JAVA. For more information, please follow other related articles on the PHP Chinese website!