连接mysql数据库：
代码案例：
public class connectMySQL {
//连接数据库字符串
private static String url = "jdbc:mysql://202.116.54.30:3306/mydb?";
//jdbc协议+数据库协议+主机协议+端口+连接数据库 //用户名
private static String user = "root";
private static String password = "root";
public static void main(String[] args) {
try {
//1.加载驱动
Class.forName("com.mysql.cj.jdbc.Driver");
//2.建立连接wen10的连接和wen7连接会有一点不同
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb1?useSSL=false&serverTimezone=UTC","root","root");
//连接成后即可操作数据库，增删改查
System.out.println("连接成后，可操作数据库，增删改查");
//关闭连接
conn.close();
Thread.sleep(2000);
System.out.println("连接关闭");
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();}}}
连接Oracle数据库
public class connectOracle {
//连接Oracle数据库字符串
private static String url = "jdb:oracle:thin:@localhost:1521:orcl";
//jdbc协议+数据库协议+主机协议+端口+连接数据库 //用户名
private static String user = "system";
private static String password = "root";
public static void main(String[] args) {
try {
//1.加载驱动
Class.forName("oracle.jdbc.driver.OracleDriver");
//2.建立连接
Connection conn = DriverManager.getConnection(url,user,password);
//连接成后即可操作数据库，增删改查
System.out.println("连接成后，可操作数据库，增删改查");
//关闭连接
conn.close();
Thread.sleep(2000);
System.out.println("连接关闭");
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();}}}
//在此省略了数据库的创建文档
public class Demo01 {
//连接数据库字符串
private static String url = "jdbc:mysql://202.116.54.30:3306/mydb?";
//jdbc协议+数据库协议+主机协议+端口+连接数据库 //用户名
private static String user = "root";
private static String password = "root";
public static void main(String[] args) {
//ShowAllEmp();
//ShowSingleEmp(7499);
//UserLogin();
//UserLogin2();
//UpdateEmp();
DeleteEmp();
}
private static void DeleteEmp() {
try {
//1.加载驱动
Class.forName("com.mysql.cj.jdbc.Driver");
//2.建立连接
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb?useSSL=false&serverTimezone=UTC","root","root");
//连接成后即可操作数据库，增删改查
Scanner input=new Scanner(System.in);
System.out.print("请输入要删除的员工编号:");
int empno=input.nextInt();
String sql="delete from emp where empno = ?";
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setInt(1, empno);
int count = pstmt.executeUpdate();
if(count > 0) {
System.out.println("员工删除成功!");
}else {
System.out.println("员工删除失败!");
}
//关闭连接
conn.close();
} catch (Exception e) {
e.printStackTrace();
}
}
private static void UpdateEmp() {
try {
//1.加载驱动
Class.forName("com.mysql.cj.jdbc.Driver");
//2.建立连接
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb?useSSL=false&serverTimezone=UTC","root","root");
//连接成后即可操作数据库，增删改查
Scanner input=new Scanner(System.in);
System.out.print("请输入员工编号:");
int empno=input.nextInt();
System.out.print("请输入员工姓名:");
String ename=input.next();
System.out.print("请输入员工 职位:");
String job=input.next();
System.out.print("请输入上司编号:");
int mgr=input.nextInt();
System.out.print("请输入入职日期(yyyy-MM-dd):");
String date=input.next();
SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
Date hiredate=sdf.parse(date);
System.out.print("请输入基本工资:");
double sal=input.nextDouble();
System.out.print("请输入奖金:");
double comm=input.nextDouble();
System.out.print("请输入部门编号(10,20,30):");
int deptno=input.nextInt();
String sql="insert into emp values(?,?,?,?,?,?,?,?)";
System.out.println(sql);
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setInt(1, empno);
pstmt.setString(2, ename);
pstmt.setString(3, job);
pstmt.setInt(4, mgr);
pstmt.setDate(5, new java.sql.Date(hiredate.getTime()));
pstmt.setDouble(6, sal);
pstmt.setDouble(7, comm);
pstmt.setInt(8, deptno);
int count = pstmt.executeUpdate();
if(count > 0) {
System.out.println("员工添加成功!");
}else {
System.out.println("员工添加错失败!");
}
//关闭连接
conn.close();
} catch (Exception e) {
e.printStackTrace();
}
}
//使用Statement对象登录
private static void UserLogin2() {
try {
//1.加载驱动
Class.forName("com.mysql.cj.jdbc.Driver");
//2.建立连接
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb?useSSL=false&serverTimezone=UTC","root","root");
//连接成后即可操作数据库，增删改查
Scanner input=new Scanner(System.in);
System.out.print("请输入用户名:");
String uname=input.nextLine();
System.out.print("请输入密码:");
String pwd=input.nextLine();
String sql="select * from user where username='"+uname+"' and password='"+pwd+"'";
System.out.println(sql);
Statement pstmt = conn.createStatement();
ResultSet rs=pstmt.executeQuery(sql);
if(rs.next()) {
System.out.println("登录成功!");
}else {
System.out.println("用户名或密码错误!");
}
conn.close();
} catch (Exception e) {
e.printStackTrace();
}
}
private static void UserLogin() {
try {
//1.加载驱动
Class.forName("com.mysql.cj.jdbc.Driver");
//2.建立连接
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb?useSSL=false&serverTimezone=UTC","root","root");
//连接成后即可操作数据库，增删改查
System.out.println("连接成后，可操作数据库，增删改查");
Scanner sc = new Scanner(System.in);
System.out.println("请输入用户名：");
String username = sc.nextLine();
System.out.println("请输入密码：");
String pwd = sc.nextLine();
//查询数据库，查找所有员工
//创建SQL语句字符串
String sql = "select * from User1 where username = ? and password = ?";
System.out.println(sql);
//定义发送SQL语句的运载工具PrepareStatement对象
PreparedStatement pstmt = conn.prepareStatement(sql);
//执行查询
pstmt.setString(1, username);
pstmt.setString(2, pwd);
ResultSet rs = pstmt.executeQuery();
//取值
//rs.next();//rs最初指向第0行，每调用一次next方法就往下移一行
if(rs.next()) {
System.out.println("登陆成功");
}else {
System.out.println("用户名或者密码输入错误");
}
//关闭连接
conn.close();
Thread.sleep(2000);
System.out.println("连接关闭");
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
private static void ShowSingleEmp(int eno) {
try {
//1.加载驱动
Class.forName("com.mysql.cj.jdbc.Driver");
//2.建立连接
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb?useSSL=false&serverTimezone=UTC","root","root");
//连接成后即可操作数据库，增删改查
System.out.println("连接成后，可操作数据库，增删改查");
//查询数据库，查找所有员工
//创建SQL语句字符串
String sql = "select * from emp where empno = ?";
System.out.println(sql);
//定义发送SQL语句的运载工具PrepareStatement对象
PreparedStatement pstmt = conn.prepareStatement(sql);
//执行查询
pstmt.setInt(1, eno);
ResultSet rs = pstmt.executeQuery();
//取值
//rs.next();//rs最初指向第0行，每调用一次next方法就往下移一行
if(rs.next()) {
//用列名
System.out.print("员工编号："+rs.getInt("empno"));
System.out.print("，姓名："+rs.getString("ename"));
System.out.print("，职位："+rs.getString("job"));
System.out.print("上司："+rs.getInt("mgr"));
System.out.print("入职日期："+rs.getDate("hiredate"));
System.out.print("基本工资："+rs.getDouble("sal"));
// //用列号
// System.out.println("员工编号："+rs.getInt(1));
// System.out.println("，姓名："+rs.getString(2));
// System.out.println("，职位："+rs.getString(3));
// System.out.println("上司："+rs.getInt(4));
// System.out.println("入职日期："+rs.getDate(5));
// System.out.println("基本工资："+rs.getDouble(6));
}
//关闭连接
conn.close();
Thread.sleep(2000);
System.out.println("连接关闭");
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
private static void ShowAllEmp() {
try {
//1.加载驱动
Class.forName("com.mysql.cj.jdbc.Driver");
//2.建立连接
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb?useSSL=false&serverTimezone=UTC","root","root");
//连接成后即可操作数据库，增删改查
System.out.println("连接成后，可操作数据库，增删改查");
//查询数据库，查找所有员工
//创建SQL语句字符串
String sql = "select * from emp";
//定义发送SQL语句的运载工具PrepareStatement对象
PreparedStatement pstmt = conn.prepareStatement(sql);
//执行查询
ResultSet rs = pstmt.executeQuery();
//取值
//rs.next();//rs最初指向第0行，每调用一次next方法就往下移一行
while(rs.next()) {
//用列名
// System.out.println("员工编号："+rs.getInt("empno"));
// System.out.println("，姓名："+rs.getString("ename"));
// System.out.println("，职位："+rs.getString("job"));
// System.out.println("上司："+rs.getInt("mgr"));
// System.out.println("入职日期："+rs.getDate("hiredate"));
// System.out.println("基本工资："+rs.getDouble("sal"));
//用列号
System.out.println("员工编号："+rs.getInt(1));
System.out.println("，姓名："+rs.getString(2));
System.out.println("，职位："+rs.getString(3));
System.out.println("上司："+rs.getInt(4));
System.out.println("入职日期："+rs.getDate(5));
System.out.println("基本工资："+rs.getDouble(6));
}
//关闭连接
conn.close();
Thread.sleep(2000);
System.out.println("连接关闭");
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}}}
具体导包文件省略，感觉连接起来跟IO流的理解运用差不多，就加上了MySQL和Oracle的语言基础
红米是你制作出了一个数据库连接的工具类，会使功能使用方便很多，也大大的简洁了代码。
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