MySQL_(Java)使用JDBC向数据库发起查询请求　　传送门

　　MySQL_(Java)使用JDBC向数据库中插入(insert)数据　　传送门

　　MySQL_(Java)使用JDBC向数据库中删除(delete)数据　　传送门

　　MySQL_(Java)使用JDBC向数据库中修改(update)数据　　传送门

　　MySQL数据库中的数据，数据库名garysql，表名garytb，修改id=1用户名密码

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

public class JDBC01 {

    public static void main(String[] args) throws SQLException  {

        update(1,"111");

    }

    public static void selectAll() throws SQLException {

        //注册驱动    使用驱动连接数据库

        Connection con = null;

        Statement stmt = null;

        ResultSet rs = null;

        try {

            //数据库的连接

            con = JDBCUtils.getConnection();

            //数据库的增删改查

            stmt = con.createStatement();

            //返回一个结果集

            rs =stmt.executeQuery("select * from garytb");

            while(rs.next()) {

                //System.out.println(rs.getString(1)+","+rs.getString(2)+","+rs.getString(3));

                System.out.println(rs.getString("id")+","+rs.getString("username")+","+rs.getString("password"));

            }

        } catch (Exception e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }finally {

            JDBCUtils.close(rs, stmt, con);

        }

    }

    //校验用户

    public static boolean  selectByUernamePassword(String username,String password) throws SQLException {

        Connection con=null;

        Statement stmt = null;

        ResultSet rs = null;

        try {

            Class.forName("com.mysql.jdbc.Driver");

            String url ="jdbc:mysql://localhost:3306/garysql?useUnicode=true&characterEncoding=UTF8&useSSL=false";

            con = DriverManager.getConnection(url,"root","123456");

            stmt =con.createStatement();

            String sql = "select * from garytb where username = '"+username+"' and password = '"+password+"'";

            //System.out.println(sql);

            rs = stmt.executeQuery(sql);

            if(rs.next()) {

                return true;

            }else {

                return false;

            }

        } catch (Exception e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }finally {

            if(rs!=null)

                rs.close();

            if(stmt!=null)

                stmt.close();

            if(con!=null)

                con.close();

        }

        return false;

    }

    public static boolean selectByUP2(String username,String password) throws SQLException{

        Connection con=null;

        Statement stmt = null;

        ResultSet rs = null;

        try {

            Class.forName("com.mysql.jdbc.Driver");

            String url ="jdbc:mysql://localhost:3306/garysql?useUnicode=true&characterEncoding=UTF8&useSSL=false";

            con = DriverManager.getConnection(url,"root","123456");

            String sql = "select * from garytb where username = ? and password = ?";

            PreparedStatement pstmt = con.prepareStatement(sql);

            //添加参数

            pstmt.setString(1, username);

            pstmt.setString(2, password);

            //进行查询

            rs = pstmt.executeQuery();

            if(rs.next()) {

                return true;

            }else {

                return false;

            }

        } catch (Exception e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }finally {

            if(rs!=null)

                rs.close();

            if(stmt!=null)

                stmt.close();

            if(con!=null)

                con.close();

        }

        return false;

    }

    //pageNumber是页数，第几页，pageCount是每页显示多少个数据

    public static void selectUserByPage(int pageNumber,int pageCount) throws SQLException {

        //注册驱动    使用驱动连接数据库

                Connection con = null;

                PreparedStatement stmt = null;

                ResultSet rs = null;

                try {

                    Class.forName("com.mysql.jdbc.Driver");

                    //String url ="jdbc:mysql://localhost:3306/garysql";

                    //指定编码查询数据库

                    String url ="jdbc:mysql://localhost:3306/garysql?useUnicode=true&characterEncoding=UTF8&useSSL=false";

                    String user = "root";

                    String password = "123456";

                    //建立和数据库的连接

                    con = DriverManager.getConnection(url,user,password);

                    stmt = con.prepareStatement("select * from garytb limit ?,?");

                    stmt.setInt(1, (pageNumber-1)*pageCount );

                    stmt.setInt(2, pageCount);

                    rs = stmt.executeQuery();

                    while(rs.next()) {

                        //System.out.println(rs.getString(1)+","+rs.getString(2)+","+rs.getString(3));

                        System.out.println(rs.getString("id")+","+rs.getString("username")+","+rs.getString("password"));

                    }

                } catch (Exception e) {

                    // TODO Auto-generated catch block

                    e.printStackTrace();

                }finally {

                    if(rs!=null)

                        rs.close();

                    if(stmt!=null)

                        stmt.close();

                    if(con!=null)

                        con.close();

                }

    }

    //crud: create read update delete

    //插入语句

    public static void insert(String username,String password) throws SQLException {

        //注册驱动    使用驱动连接数据库

        Connection con = null;

        PreparedStatement stmt = null;

        ResultSet rs = null;

        try {

            con = JDBCUtils.getConnection();

            String sql = "insert into garytb(username,password) values(?,?)";

            stmt = con.prepareStatement(sql);

            stmt.setString(1, username);

            stmt.setString(2, password);

            int result =stmt.executeUpdate();// 返回值代表收到影响的行数

            System.out.println("插入成功"+username);

        } catch (Exception e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }finally {

            JDBCUtils.close(rs, stmt, con);

        }

    }

    //删除语句

    public static void delete(int id) throws SQLException {

        //注册驱动    使用驱动连接数据库

        Connection con = null;

        PreparedStatement stmt = null;

        ResultSet rs = null;

        try {

            con = JDBCUtils.getConnection();

            String sql = "delete from garytb where id = ?";

            stmt = con.prepareStatement(sql);

            stmt.setInt(1, id);

            int result =stmt.executeUpdate();// 返回值代表收到影响的行数

            if(result>0) {

                System.out.println("删除成功");

            }else {

                System.out.println("删除失败");

            }

        } catch (Exception e) {

            e.printStackTrace();

        } finally {

            JDBCUtils.close(rs, stmt, con);

        }

    }

    //修改语句

    public static void update(int id,String newPassword) throws SQLException {

        Connection con = null;

        PreparedStatement stmt = null;

        ResultSet rs = null;

        try {

            con = JDBCUtils.getConnection();

            String sql = "update garytb set password = ? where id = ?";

            stmt = con.prepareStatement(sql);

            stmt.setString(1, newPassword);

            stmt.setInt(2, id);

            int result =stmt.executeUpdate();// 返回值代表收到影响的行数

            if(result>0) {

                System.out.println("修改成功");

            }else {

                System.out.println("修改失败");

            }

        } catch (Exception e) {

            e.printStackTrace();

        } finally {

            JDBCUtils.close(rs, stmt, con);

        }

    }

}

JDBC01.java

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

public class JDBCUtils {

    private static final String connectionURL = "jdbc:mysql://localhost:3306/garysql?useUnicode=true&characterEncoding=UTF8&useSSL=false";

    private static final String username = "root";

    private static final String password = "123";

    //创建数据库的连接

    public static Connection getConnection() {

        try {

            Class.forName("com.mysql.jdbc.Driver");

            return   DriverManager.getConnection(connectionURL,username,password);

        } catch (Exception e) {

            e.printStackTrace();

        }

        return null;

    }

    //关闭数据库的连接

    public static void close(ResultSet rs,Statement stmt,Connection con) throws SQLException {

        if(rs!=null)

            rs.close();

        if(stmt!=null)

            stmt.close();

        if(con!=null)

            con.close();

    }

}

JDBCUtils.java

　　根据id修改数据库中的数据

public static void update(int id,String newPassword) throws SQLException {

        Connection con = null;

        PreparedStatement stmt = null;

        ResultSet rs = null;

        try {

            con = JDBCUtils.getConnection();

            String sql = "update garytb set password = ? where id = ?";

            stmt = con.prepareStatement(sql);

            stmt.setString(1, newPassword);

            stmt.setInt(2, id);

            int result =stmt.executeUpdate();// 返回值代表收到影响的行数

            if(result>0) {

                System.out.println("修改成功");

            }else {

                System.out.println("修改失败");

            }

        } catch (Exception e) {

            e.printStackTrace();

        } finally {

            JDBCUtils.close(rs, stmt, con);

        }

    }

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