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Operation code for database part knowledge using JAVA
- php是最好的语言Original
- 2018-08-07 14:09:031399browse
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)
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)
, alter, drop
. Language: control authority) revork, grant; 5. (Integrity Conditions) Constraints: 1. Primary key constraint
2. Foreign key 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：
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