Java-mysql-000-連接、插入、查詢、修改、刪除-2020-6-25
一、connect.java
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class connect {
public static void main(String[] args) {
//聲明Connection對象
Connection con;
//驅動程序名
String driver = "com.mysql.cj.jdbc.Driver";
//URL指向要訪問的數據庫名mysql（此處的test是你所javatest的那個database）
String url = "jdbc:mysql://localhost:3306/javatest?useSSL=false&serverTimezone=UTC";
//MySQL配置時的用戶名
String user = "root";
//MySQL配置時的密碼
String password = "123456789";
//遍歷查詢結果集
try {
//加載驅動程序
Class.forName(driver);
//1.getConnection()方法，連接MySQL數據庫！！
con = DriverManager.getConnection(url,user,password);
if(!con.isClosed())
System.out.println("Succeeded connecting to the Database!");
//2.創建statement類對象，用來執行SQL語句！！
Statement statement = con.createStatement();
//要執行的SQL語句
String sql = "select * from student";
//3.ResultSet類，用來存放獲取的結果集！！
ResultSet rs = statement.executeQuery(sql);
System.out.println("執行結果如下所示:");
System.out.println("-----------------");
System.out.println("姓名" + "\t" + "年齡"+ "\t" + "職位");
System.out.println("-----------------");
String name = null;
String position = null;
int age=0;
while(rs.next()){
//獲取name這列數據
name = rs.getString("name");
//獲取age這列數據
age=rs.getInt("age");
//獲取position這列數據
position = rs.getString("position");
//輸出結果
System.out.println(name + "\t" + age + "\t" + position);
}
rs.close();
con.close();
} catch(ClassNotFoundException e) {
//數據庫驅動類異常處理
System.out.println("Sorry,can`t find the Driver!");
e.printStackTrace();
} catch(SQLException e) {
//數據庫連接失敗異常處理
e.printStackTrace();
}catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}finally{
System.out.println("數據庫數據成功獲取！！");
}
}
}
二、insert.java
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
public class insert {
public static void main(String[] args) {
try {
// 加載數據庫驅動
Class.forName("com.mysql.cj.jdbc.Driver");
// 聲明數據庫view的URL
String url = "jdbc:mysql://localhost:3306/javatest?useSSL=false&serverTimezone=UTC";
// 數據庫用戶名
String user = "root";
// 數據庫密碼
String password = "123456789";
// 建立數據庫連接，獲得連接對象conn
Connection con = DriverManager.getConnection(url, user, password);
String sql = "insert into student (name,age,position) values(?,?,?)"; // 生成一條sql語句
// 創建一個Statment對象
PreparedStatement ps = con.prepareStatement(sql);
// 爲sql語句中第一個問號賦值
ps.setString(1, "李四");
// 爲sql語句中第二個問號賦值
ps.setInt(2, 123);
// 爲sql語句中第三個問號賦值
ps.setString(3, "插入");
// 爲sql語句中第四個問號賦值
// 執行sql語句
ps.executeUpdate();
// 關閉數據庫連接對象
con.close();
System.out.println("數據變化");
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
三、delete.java
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
public class delete {
public static void main(String[] args) {
try {
// 加載數據庫驅動
Class.forName("com.mysql.cj.jdbc.Driver");
// 聲明數據庫view的URL
String url = "jdbc:mysql://localhost:3306/javatest?useSSL=false&serverTimezone=UTC";
// 數據庫用戶名
String user = "root";
// 數據庫密碼
String password = "123456789";
// 建立數據庫連接，獲得連接對象conn
Connection con = DriverManager.getConnection(url, user, password);
String sql = "delete from student where age = ?";
PreparedStatement stmt = con.prepareStatement(sql);
stmt.setInt(1, 123);
int result =stmt.executeUpdate();// 返回值代表收到影響的行數
if(result>0) {
System.out.println("刪除成功");
}else {
System.out.println("刪除失敗");
}
con.close();
System.out.println("數據變化");
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
四、update.java
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
public class update {
public static void main(String[] args) {
try {
// 加載數據庫驅動
Class.forName("com.mysql.cj.jdbc.Driver");
// 聲明數據庫view的URL
String url = "jdbc:mysql://localhost:3306/javatest?useSSL=false&serverTimezone=UTC";
// 數據庫用戶名
String user = "root";
// 數據庫密碼
String password = "123456789";
// 建立數據庫連接，獲得連接對象conn
Connection con = DriverManager.getConnection(url, user, password);
String sql = "update student set name = ? where age = ?";
PreparedStatement stmt = con.prepareStatement(sql);
stmt.setString(1, "小云");
stmt.setInt(2, 12);
int result =stmt.executeUpdate();// 返回值代表收到影響的行數
if(result>0) {
System.out.println("修改成功");
}else {
System.out.println("修改失敗");
}
con.close();
System.out.println("數據變化");
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}