PreparedStatement进行数据库增删改查

1 插入数据

public boolean ChaRu3(User user){        boolean flag=true;        Connection conn=null;        PReparedStatement ps=null;    //创建PreparedStatement 对象        String sql= "insert into user (name,pwd) values(?,?)";  //sql语句不再采用拼接方式，应用占位符问号的方式写sql语句。        conn=DBConnUtil.getConn();        try {            ps=conn.prepareStatement(sql);            ps.setString(1, user.getName()); //对占位符设置值，占位符顺序从1开始，第一个参数是占位符的位置，第二个参数是占位符的值。            ps.setString(2, user.getPwd());             int i=ps.executeUpdate();            if(i==0){                flag=false;            }        } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }finally{            DBConnUtil.closeAll(null, ps, conn);        }        return flag;            }
 
2 修改数据
 
public boolean XiuGai3(User user){        boolean flag=true;        Connection conn=null;        PreparedStatement ps=null;        String sql="update user set pwd=? where name=?";        conn=DBConnUtil.getConn();        try {            ps=conn.prepareStatement(sql);            ps.setString(1, user.getPwd());            ps.setString(2, user.getName());            int i= ps.executeUpdate();            if(i==0){                flag=false;            }                    } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }finally{            DBConnUtil.closeAll(null, ps, conn);        }        return flag;    }
 
3 删除数据
public boolean ShanChu3(int id){        boolean flag=true;        Connection conn=null;        PreparedStatement ps=null;        String sql="delete from user where id=?";        conn=DBConnUtil.getConn();        try {            ps=conn.prepareStatement(sql);            ps.setInt(1, id);            int i=ps.executeUpdate();            if(i==0){                flag=false;            }        } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }finally{            DBConnUtil.closeAll(null, ps, conn);        }                return flag;    }
 
4 查看数据
public List<User> ChaKan3(){         List<User> list= new ArrayList<User>();         Connection conn=null;         PreparedStatement ps=null;         ResultSet rs=null;         String sql="select * from user";         conn=DBConnUtil.getConn();         try {               ps=conn.prepareStatement(sql);             rs=ps.executeQuery();             while(rs.next()){                User user= new User();                user.setName(rs.getString("name"));                list.add(user);             }        } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }finally{            DBConnUtil.closeAll(rs, ps, conn);        }                 return list;     }