Day11——增删改操作获取对数据库的影响条数

╰+哭是因爲堅強的太久メ 2023-07-04 12:54 13阅读 0赞

# 一. 问题分析 #

有时候对数据库进行增删改，想要它返回一个影响条数，判断它能不能正常执行。

# 二. 知识储备 #

只需将Mapper接口的返回值类型改为你想要获取的类型即可。比如Integer、Long、Boolean。

# 三. 例子 #

如下：  
EmployeeMapper.java

package com.atguigu.mybatis.dao;
    
    import com.atguigu.mybatis.beans.Employee;
    
    public interface EmployeeMapper { 
    
    	public Employee selectEmployeeById(Integer id);
    	
        public Integer insertEmployee(Employee employee);
        
        public Long updateEmployee(Employee employee);
        
        public Boolean deleteEmployeeById(Integer id);
    	
    }

TestMyBatis.java

@Test
    	public void testReturnKeys() throws Exception{ 
    		SqlSessionFactory ssf = getSqlSessionFactory();
    		SqlSession session = ssf.openSession();
    		//ssf.openSession(true);带自动提交功能
    		try { 
    			EmployeeMapper mapper = session.getMapper(EmployeeMapper.class);
    			Employee employee = new Employee(null, "优优", "yy@sina.com", "1");
    			
    			Integer result = mapper.insertEmployee(employee);
    			System.out.println("对数据库的影响：" + result);
    			
    			Integer id = employee.getId();
    			System.out.println("主键值：" + id);
    			
    			session.commit();
    			
    			
    			/** * 底层源码实现主键自增并且返回主键 */
    // 
    // Connection conn = null;
    // PreparedStatement ps = 
    // conn.prepareStatement("sql语句", PreparedStatement.RETURN_GENERATED_KEYS);
    // ps.executeUpdate();
    // ps.getGeneratedKeys();
    			
    		} finally { 
    			// TODO: handle finally clause
    			session.close();
    		}
    		
    	}