SqlSession三种增删改查的方式

你的名字 2024-03-25 19:58 77阅读 0赞

**SqlSession三种查询的方式**

//查询方式一 使用于查询多条数据的时候，返回一个集合
            List<Flower> list = sqlSession.selectList("com.bzsxt.mapper.FlowerMapper.selectAll");
            //查询方式二 查询某一个，返回查询的对象
            Object selectOne = sqlSession.selectOne("com.bzsxt.mapper.FlowerMapper.selectOne");
            //查询方式三 第二个参数作为map的key传入，通过get方法快速查询到某一条数据
            Map<Object, Object> selectMap = sqlSession.selectMap("com.bzsxt.mapper.FlowerMapper.selectAll", "fname");
            Object value = selectMap.get("紫罗兰");

**SqlSession三种参数传递的方式**

//当参数类型是基本数据类型时：
            Object selectOne = sqlSession.selectOne("com.bzsxt.mapper.FlowerMapper.selectOne", 10);
            //当参数类型是某一个类时,可以传递多个参数：
            Flower flower = new Flower();
            flower.setPrice(5);
            flower.setFname("夕颜");
            Object selectOne1 = sqlSession.selectOne("com.bzsxt.mapper.FlowerMapper.selectOne2", flower);
            System.out.println(selectOne1);
            //当参数类型为map时，key值作为查询的？,value代表查询的具体值
            Map<Object,Object> map = new HashMap<>();
            map.put("a",10);
            map.put("b","紫罗兰");
            Object selectOne3 = sqlSession.selectOne("com.bzsxt.mapper.FlowerMapper.selectOne3", map);
            System.out.println(selectOne3);
            sqlSession.close();

**三种参数传递对应的xml文件**

<select id="selectOne" resultType="flower" parameterType="int">
            select * from flower where fid = #{param1}
        </select>
        
        <select id="selectOne2" resultType="flower" parameterType="flower">
            select * from flower where price = #{price} and fname = #{fname}
        </select>
        
        <select id="selectOne3" resultType="flower" parameterType="map">
            select * from flower where fid = #{a} and fname = #{b}
        </select>

**增删改的操作**

//增加数据的操作insert
            Flower flower = new Flower();
            flower.setPrice(99);
            flower.setFname("西蓝花");
            flower.setVariety("美国");
            int insert = sqlSession.insert("com.bzsxt.mapper.FlowerMapper.insert",flower);
            //修改操作
            Flower flower = new Flower();
            flower.setPrice(3);
            flower.setFname("大白菜");
            flower.setFid(12);
            int update = sqlSession.update("com.bzsxt.mapper.FlowerMapper.update", flower);
            //删除操作delete
            int delete = sqlSession.delete("com.bzsxt.mapper.FlowerMapper.delete", 13);
            //需要提交事务，否则不会写到数据库

**增删改对应的xml文件**

<insert id="insert" parameterType="flower">
            insert into flower values(default,#{fname},#{variety},#{price})
        </insert>
        
        <insert id="update" >
            update flower set fname = #{fname},price = #{price} where fid = #{fid}
        </insert>
        
        <delete id="delete">
            delete from flower where fid = #{param1}
        </delete>

\[1\]mybatis中parameterType 这个属性可以省略的 但是 resultType 是不可以省略的

\[2\]\#\{\} 相当于占位符 $\{\} 相当于拼接

提交的两种方式

\[1\]session.commit();

\[2\]SqlSession session = factory.openSession(true);

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原文链接：[https://blog.csdn.net/u014193754/article/details/118404075][https_blog.csdn.net_u014193754_article_details_118404075]

[https_blog.csdn.net_u014193754_article_details_118404075]: https://blog.csdn.net/u014193754/article/details/118404075