studentms/Coursemdaoimplqsy.java

package com.WR.StudentMS.dao.mysql;

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

import com.WR.StudentMS.dao.Coursemdaoqsy;
import com.WR.StudentMS.model.Coursemqsy;


public class Coursemdaoimplqsy implements Coursemdaoqsy {

	@Override
	public List<Coursemqsy> findAllqsy() {
		String sql = "select id,name,jieshao from t_kecheng";
		List<Coursemqsy> coursemqsy = new ArrayList<Coursemqsy>();

		try (
				
				Connection conn = DBHelper.getConnection();
				
				PreparedStatement pstmt = conn.prepareStatement(sql);
				
				
				ResultSet rs = pstmt.executeQuery()) {

			
			while (rs.next()) {
                Coursemqsy coursem = new Coursemqsy();
                coursem.setCourseidqsy(rs.getString("id"));
                coursem.setCoursenameqsy(rs.getString("name"));
                coursem.setJieshaoqsy(rs.getString("jieshao"));
                coursemqsy.add(coursem);
			}

		} catch (SQLException e) {
			e.printStackTrace();
		}
		return coursemqsy;
	}

	@Override
    public Coursemqsy findByIdqsy(String courseid) {
        String sql = "SELECT id, name, jieshao FROM t_kecheng WHERE id = ?";
        try (
            Connection conn = DBHelper.getConnection();
            PreparedStatement pstmt = conn.prepareStatement(sql);
        ) {
            pstmt.setString(1, courseid);
            ResultSet rs = pstmt.executeQuery();
            if (rs.next()) {
                Coursemqsy coursem = new Coursemqsy();
                coursem.setCourseidqsy(rs.getString("id"));
                coursem.setCoursenameqsy(rs.getString("name"));
                coursem.setJieshaoqsy(rs.getString("jieshao"));
                return coursem;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return null;
    }


	@Override
	public int createqsy(Coursemqsy coursem) {
	    String sql = "insert into t_kecheng (id, name, jieshao) values (?,?,?)";
	    try (
	            Connection conn = DBHelper.getConnection();
	            PreparedStatement pstmt = conn.prepareStatement(sql)
	    ) {
	        pstmt.setString(1, coursem.getCourseidqsy());
	        pstmt.setString(2, coursem.getCoursenameqsy());
	        pstmt.setString(3, coursem.getJieshaoqsy()); // 确保这里的占位符数量与SQL语句中的一致

	        int affectedRows = pstmt.executeUpdate();
	        System.out.printf("成功插入%d条数据\n", affectedRows);
	        return affectedRows; // 如果插入成功，返回受影响的行数
	    } catch (SQLException e) {
	        // 打印异常信息，以便于调试
	        e.printStackTrace();
	        // 如果发生异常，返回-1表示操作失败
	        return -1;
	    }
	}
	

	@Override
	public int removeqsy(Coursemqsy coursem) {
	    String sql = "delete from t_kecheng where id = ?"; // 只使用 id 作为删除条件
	    try (
	            Connection conn = DBHelper.getConnection();
	            PreparedStatement pstmt = conn.prepareStatement(sql)
	    ) {
	        pstmt.setString(1, coursem.getCourseidqsy()); // 设置要删除的课程的 id
	        int affectedRows = pstmt.executeUpdate();
	        System.out.printf("成功删除%d条数据\n", affectedRows); // 修正控制台输出信息
	        return affectedRows; // 返回受影响的行数
	    } catch (SQLException e) {
	        e.printStackTrace(); // 打印异常信息
	        return -1; // 发生异常时返回-1
	    }
	}
}