lsispig/Attendanceimpl.java

package com.system.impl;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import com.system.dao.AttendanceDao;
import com.system.javaBean.Attendance;
import com.system.utils.DB;

public class Attendanceimpl implements AttendanceDao {
    private Connection conn;
    private DB dataBase = new DB();

   
   

   

    @Override
    public List<Attendance> statisticsAttendance(String sno) throws SQLException {
        List<Attendance> statistics = new ArrayList<>();
        conn = dataBase.getConnection();
        try (PreparedStatement pstmt = conn.prepareStatement("SELECT cno, COUNT(*) as total_attendance, " +
                "SUM(CASE WHEN status = 'Present' THEN 1 ELSE 0 END) as present_count, " +
                "SUM(CASE WHEN status <> 'Present' THEN 1 ELSE 0 END) as absent_count " +
                "FROM attendance WHERE sno = ? GROUP BY cno")) {
            pstmt.setString(1, sno);
            ResultSet rs = pstmt.executeQuery();
            while (rs.next()) {
                Attendance attendance = new Attendance();
                attendance.setCourseCno(rs.getString("cno"));
                attendance.setId(rs.getString("id")); // 注意：这里假设id字段用来存储总考勤次数
                attendance.setStatus(rs.getString("present_count") + "/" + rs.getString("absent_count"));
                statistics.add(attendance);
            }
        } catch (SQLException e) {
            throw new SQLException("Error calculating attendance statistics", e);
        } finally {
            if (conn != null) {
                conn.close();
            }
        }
        return statistics;
    }

	@Override
	public boolean deleteAttendance(String id) throws SQLException {
		try {
			conn = dataBase.getConnection();
			Statement stat = null;
			stat = conn.createStatement();
			String sql = "DELETE FROM attendance WHERE id = '"+id+"' ";		
			if ( stat.executeUpdate(sql)==1 ){
				return true;
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		conn.close();
		return false;
	}

	public List<Attendance> queryByStudentId(String studentId) {
	    List<Attendance> attendanceList = new ArrayList<>();
	    // 假设您有一个可以执行数据库操作的数据库访问对象，例如使用JDBC
	    String sql = "SELECT id, sno, name,cno, date, status " +
	                 "FROM attendance " +
	                 "WHERE sno = ?";
	  	    try (Connection conn = dataBase.getConnection();
	  	         PreparedStatement pstmt = conn.prepareStatement(sql)) {
	  	        pstmt.setString(1, studentId);
	  	        ResultSet rs = pstmt.executeQuery();
	  	        while (rs.next()) {
	  	            Attendance attendance = new Attendance();
	  	            attendance.setId(rs.getString("id"));
	  	            attendance.setStudentId(rs.getString("sno"));
	  	            attendance.setName(rs.getString("name"));
	  	            attendance.setCourseCno(rs.getString("cno"));
	  	            attendance.setDate(rs.getString("date"));
	            attendance.setStatus(rs.getString("status"));
	            attendanceList.add(attendance);
	        }
	    } catch (SQLException e) {
	        // 处理异常
	        e.printStackTrace();
	    }
	    return attendanceList;
	}

	public Attendance select(String sno) {
		 Attendance attendance = null;
	        String sql = "SELECT id, sno, cno, date, status, name " +
	                     "FROM attendance " +
	                     "WHERE sno = ?";

	        try (Connection conn = dataBase.getConnection();
	             PreparedStatement pstmt = conn.prepareStatement(sql)) {
	            pstmt.setString(1, sno);
	            ResultSet rs = pstmt.executeQuery();

	            if (rs.next()) {
	                attendance = new Attendance();
	                String id = rs.getString("id");
	               
	                 String name = rs.getString("name");
	                String cno = rs.getString("cno");
	                String date = rs.getString("date"); // 这里假设数据库中的日期是以字符串形式存储的
	                String status = rs.getString("status");
	               
	                attendance.setId(id);
	                // 如果您的数据库中的日期是以LocalDate形式存储的，您需要进行相应的转换
	                // 例如：LocalDate.parse(date, DateTimeFormatter.ofPattern("yyyy-MM-dd"));
	                attendance.setDate(date);
	                attendance.setStudentId(sno); // 已经作为查询条件，可以直接赋值
	                 attendance.setName(name);
	                attendance.setCourseCno(cno);
	                attendance.setStatus(status);
	               
	            }
	        } catch (SQLException e) {
	            // 处理异常
	            e.printStackTrace();
	        }
	        return attendance;
	    }

	// 更新课程
			@Override
			public boolean updateById(String id, String sno, String name, String cno, String date, String status) throws SQLException {
			    try {
			        conn = dataBase.getConnection();
			        // 使用PreparedStatement来防止SQL注入
			        String sql = "UPDATE attendance SET sno = ?, name = ?, cno = ?, date = ?, status = ? WHERE id = ?";
			        try (PreparedStatement pstmt = conn.prepareStatement(sql)) {
			            // 按顺序设置参数值
			            pstmt.setString(1, sno);
			            pstmt.setString(2, name);
			            pstmt.setString(3, cno);
			            pstmt.setString(4, date);
			            pstmt.setString(5, status);
			            pstmt.setString(6, id); // WHERE条件

			            // 执行更新操作
			            int affectedRows = pstmt.executeUpdate();
			            // 检查是否至少有一行被更新
			            return affectedRows > 0;
			        }
			    } catch (SQLException e) {
			        e.printStackTrace();
			        throw e; // 重新抛出异常，以便调用者可以处理它
			    }
			}
		// 更新课程中的查找
		

		@Override
		public Attendance selectById(String id) throws SQLException {
			 // 编写SQL查询语句
		    String sql = "SELECT * FROM attendance WHERE id = ?";
		    try (Connection conn = dataBase.getConnection();
		         PreparedStatement pstmt = conn.prepareStatement(sql)) {
		        pstmt.setString(1, id);
		        ResultSet rs = pstmt.executeQuery();
		        if (rs.next()) {
		            Attendance attendance = new Attendance();
		            // 填充Attendance对象的数据
		            attendance.setId(rs.getString("id"));
		            attendance.setStudentId(rs.getString("sno"));
		            attendance.setName(rs.getString("name"));
		            attendance.setCourseCno(rs.getString("cno"));
		            attendance.setDate(rs.getString("date"));
		            attendance.setStatus(rs.getString("status"));
		            return attendance;
		        }
		    } catch (SQLException e) {
		        throw new SQLException("Error selecting attendance record", e);
		    }
		    return null; // 如果没有找到记录
		}
		}