java使用mapper操作mysql

上半部分搭建springboot 简单使用数据库查询
添加链接描述

在impl接口实现操作

如

package com.service.impl;
import com.dao.UserMapper;
import com.pojo.User;
import com.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
@Service
public class UserServiceImpl implements UserService {
    @Autowired
    private UserMapper userMapper;
    @Override
    public List dade() {
        return userMapper.selectAll();
    }
    @Override
    public User oneUser(Long id) {
        return userMapper.selectByPrimaryKey(id);
    }
}
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1、selectAll查所有

	@Override
    public List dade() {
        return userMapper.selectAll();
    }
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2、selectByPrimaryKey根据id查询

    @Override
    public User oneUser(Long id) {
        return userMapper.selectByPrimaryKey(id);
    }
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3、insert保存

    @Override
    public User oneUser(Long id) {
        User user = new User();
        user.setAge((long) 18);
        user.setName("dade");
        user.setPhone("14796178000");
        user.setDate("2023-12-23");
        userMapper.insert(user);
        return userMapper.selectByPrimaryKey(id);
    }
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4、updateByPrimaryKey修改

    @Override
    public User oneUser(Long id) {
        User user = userMapper.selectByPrimaryKey(id);
        user.setName("大得");
        userMapper.updateByPrimaryKey(user);
        return userMapper.selectByPrimaryKey(id);
    }
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5、deleteByPrimaryKey删除

    @Override
    public User oneUser(Long id) {
        userMapper.deleteByPrimaryKey(2);
        return userMapper.selectByPrimaryKey(id);
    }
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6、selectByExample多条件查询

@Override
    public List oneUser(Long id) {
        Example example=new Example(User.class);
        Example.Criteria criteria = example.createCriteria();
        //根据id查询
        criteria.andEqualTo("id", 3);
        //模糊查询
        criteria.andLike("name","%d%");
        return userMapper.selectByExample(example);
    }
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