增删改查——PreparedStatement接口

Love The Way You Lie 2023-08-17 16:09 13阅读 0赞

1、添加

package pers.Pre.add;
    
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    
    public class Add {
        public static void main(String[] args) {
            Connection con = null;
            PreparedStatement ps = null;
    
            try {
                Class.forName("com.mysql.jdbc.Driver");
                String url = "jdbc:mysql://localhost:3306/student mangement system";
                String username = "root";
                String password = "root";
                con = DriverManager.getConnection(url, username, password);
                String insertSql = "insert into score(studentno,courseno,usually,final)values(?,?,?,?)";
                ps = con.prepareStatement(insertSql);// 获取预处理对象
                ps.setString(1, "20191832");
                ps.setString(2, "b221");
                ps.setDouble(3, 123);
                ps.setDouble(4, 123);
                int num = ps.executeUpdate();
                System.out.println("添加了" + num + "条记录");
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                try {
                    if (ps != null)
                        ps.close();
                    if (con != null)
                        con.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
    
        }
    }

2、删除

package pers.Pre.jdbc;
    
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    
    public class DeleteDemo {
        public static void main(String[] args) {
            Connection con = null;
            PreparedStatement ps = null;
    
            try {
                Class.forName("com.mysql.jdbc.Driver");
                String url = "jdbc:mysql://localhost:3306/student mangement system";
                String username = "root";
                String password = "root";
                con = DriverManager.getConnection(url, username, password);
                String deleteSql = "Delete from Student where sname=?";
                ps = con.prepareStatement(deleteSql);// 获取预处理对象
                ps.setString(1,"秀儿");
                int num = ps.executeUpdate();
                System.out.println("删除了" + num + "条信息");
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                try {
                    if (ps != null)
                        ps.close();
                    if (con != null)
                        con.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
    
            }
    
        }
    
    }

3、修改

package pers.Pre.jdbc;
    
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    
    public class UpdateDemo {
        public static void main(String[] args) {
            Connection con = null;
            PreparedStatement ps = null;
    
            try {
                Class.forName("com.mysql.jdbc.Driver");
                String url = "jdbc:mysql://localhost:3306/student mangement system";
                String username = "root";
                String password = "root";
                con = DriverManager.getConnection(url, username, password);
                String updateSql = "Update Login set password=? where account ='学前班秀儿'";
                ps = con.prepareStatement(updateSql);// 获取预处理对象
                ps.setString(1,"201908");
                int num = ps.executeUpdate();
                System.out.println("更改了" + num + "条信息");
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                try {
                    if (ps != null)
                        ps.close();
                    if (con != null)
                        con.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
    
            }
    
        }
    
    }

4、查询

package pers.Pre.jdbc;
    
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    
    public class SelectDemo {
        public static void main(String[] args) {
            Connection con = null;
            PreparedStatement ps = null;
            ResultSet rs = null;
    
            try {
                Class.forName("com.mysql.jdbc.Driver");
                String url = "jdbc:mysql://localhost:3306/student mangement system";
                String username = "root";
                String password = "root";
                con = DriverManager.getConnection(url, username, password);
                String selectSql = "select * from score";
                ps = con.prepareStatement(selectSql);// 获取预处理对象
                rs = ps.executeQuery(); 
                System.out.println("     "+"学号"+"                        "+"班级"+"           "+"平时成绩"+"    "+"期末成绩");
                while (rs.next()) {
                
                    System.out.println( rs.getString(1)+"  "+rs.getString(2)+"  "+rs.getString(3)+"  "+
                            rs.getString(4));
                }
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                try {
                    if (ps != null)
                        ps.close();
                    if (con != null)
                        con.close();
                    if (rs!=null)
                        rs.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
    
            }
    
        }
    
    }

5、Statement接口与PreparedStatement接口的对比

Statement接口用于处理不带参数的静态sql语句，PreparedStatement接口可以处理带参数的sql语句。

转载于:https://www.cnblogs.com/zhai1997/p/11376248.html