MySQL_(Java)使用JDBC向数据库中删除(delete)数据

 

 

　　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，删除数据库id=2的数据

 

 

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  {
        delete(2);
    }

    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 updata 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);
        }
    }

    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);
        }
    }
}

 

　　根据id删除数据库中的数据表

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);
        }
    }