Java connects to MySQL database (including steps and code)

Java connects to MySQL database - including steps and code

Tool: eclipse

MySQL5.6

MySQL connection driver: mysql-connector-java-5.1.27 .jar

Load the driver:

1. Create a lib folder in the project directory and place the downloaded JDBC in the folder, as shown in the following figure:

　

　2. Right-click the project name, select Add JARs... in the Libraries tab in the java build path, and select the JDBC just added, as shown below:

　

Data package preparation:

Create the following data table emp in the database sqltestdb:

CREATE TABLE emp(
   empno            INT(4)          PRIMARY KEY,
   ename            VARCHAR(10),
   job              VARCHAR(9),
   hiredate         DATE,
   sal              FLOAT(7,2)
) ;

Add data:

Connect to the database and read data:

Database name: sqltestdb

Data package name: emp

Port number: 3306

User name: root

Password: root

 1 package sqldemo; 2  3 import java.sql.Connection; 4 import java.sql.DriverManager; 5 import java.sql.ResultSet; 6 import java.sql.SQLException; 7 import java.sql.Statement; 8  9 public class main {10 11     public static void main(String[] args) {12         //声明Connection对象13         Connection con;14         //驱动程序名15         String driver = "com.mysql.jdbc.Driver";16         //URL指向要访问的数据库名mydata17         String url = "jdbc:mysql://localhost:3306/sqltestdb";18         //MySQL配置时的用户名19         String user = "root";20         //MySQL配置时的密码21         String password = "123456";22         //遍历查询结果集23         try {24             //加载驱动程序25             Class.forName(driver);26             //1.getConnection()方法，连接MySQL数据库！！27             con = DriverManager.getConnection(url,user,password);28             if(!con.isClosed())29                 System.out.println("Succeeded connecting to the Database!");30             //2.创建statement类对象，用来执行SQL语句！！31             Statement statement = con.createStatement();32             //要执行的SQL语句33             String sql = "select * from emp";34             //3.ResultSet类，用来存放获取的结果集！！35             ResultSet rs = statement.executeQuery(sql);36             System.out.println("-----------------");37             System.out.println("执行结果如下所示:");  
38             System.out.println("-----------------");  
39             System.out.println("姓名" + "\t" + "职称");  
40             System.out.println("-----------------");  
41              42             String job = null;43             String id = null;44             while(rs.next()){45                 //获取stuname这列数据46                 job = rs.getString("job");47                 //获取stuid这列数据48                 id = rs.getString("ename");49 50                 //输出结果51                 System.out.println(id + "\t" + job);52             }53             rs.close();54             con.close();55         } catch(ClassNotFoundException e) {   
56             //数据库驱动类异常处理57             System.out.println("Sorry,can`t find the Driver!");   
58             e.printStackTrace();   
59             } catch(SQLException e) {60             //数据库连接失败异常处理61             e.printStackTrace();  
62             }catch (Exception e) {63             // TODO: handle exception64             e.printStackTrace();65         }finally{66             System.out.println("数据库数据成功获取！！");67         }68     }69 70 }

## Running result:

Succeeded connecting to the Database!
-----------------
执行结果如下所示:
-----------------
姓名  职称
-----------------
李兴华 经理
张三  总监
王五  厂长
齐秦  书记
张刚  组长
曹操  财务
李四  总裁
数据库数据成功获取！！

Add, delete and modify data:

Add data:

String name;
String id;
  
PreparedStatement psql;
ResultSet res;
//预处理添加数据，其中有两个参数--“？”
psql = con.prepareStatement("insert into emp (empno,ename,job,hiredate,sal) "
        + "values(?,?,?,?,?)");
psql.setInt(1, 3212);              //设置参数1，创建id为3212的数据
psql.setString(2, "王刚");      //设置参数2，name 为王刚
psql.setString(3, "总裁");
 
DateFormat dateFormat2 = new SimpleDateFormat("yyyy-MM-dd");
Date myDate2 = dateFormat2.parse("2010-09-13");
psql.setDate(4,new java.sql.Date(myDate2.getTime()));
psql.setFloat(5, (float) 2000.3);
psql.executeUpdate();           //执行更新

Run results:

Update data:

　PreparedStatement psql;
//预处理更新（修改）数据，将王刚的sal改为5000.0
psql = con.prepareStatement("update emp set sal = ? where ename = ?");
psql.setFloat(1,(float) 5000.0);      
psql.setString(2,"王刚");             
psql.executeUpdate();

Change results:

Delete data:

PreparedStatement psql;
//预处理删除数据
psql = con.prepareStatement("delete from emp where sal > ?");
psql.setFloat(1, 4500);
psql.executeUpdate();
psql.close();

Delete result:

　

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