java JDBC 连接数据库（增删查改）

必须先插入工具包

在这里插入图片描述

代码

 public static void main(String[] args) {DataSource ds = JdbcHelper.getDs();System.out.println(ds);JdbcTemplate jdbcTemplate=new JdbcTemplate(ds);System.out.println(jdbcTemplate);//新增String sql1="insert into biao values(null,?,?,?)";int i=jdbcTemplate.update(sql1,"6",6,"6");System.out.println(i);//删除String sql2="delete from biao where id=?";int a=jdbcTemplate.update(sql2,"2");System.out.println(a);//修改String sql3="update  biao set name=? where id=2";int b=jdbcTemplate.update(sql3,"小军");System.out.println(b);//查询单个数据String sql4="select *from biao where id=?";Map<String, Object> stringObjectMap = jdbcTemplate.queryForMap(sql4,3);System.out.println(stringObjectMap);//查询多个数据String sql5="select * from biao where id>?";List<Map<String, Object>> maps = jdbcTemplate.queryForList(sql5, 5);System.out.println(maps);String sql6="select id(3) from biao where age>?";String s = jdbcTemplate.queryForObject(sql6, String.class, 20);System.out.println(s);}

！！！查询！！！

![在这里插入图片描述](https://img-blog.csdnimg.cn/direct/0e9185bf852740c584658d608c3101af.png

查询

 public static void main(String[] args) {DataSource ds = JdbcHelper.getDs();System.out.println(ds);JdbcTemplate jdbcTemplate=new JdbcTemplate(ds);System.out.println(jdbcTemplate);String sql="select * from biao where id>?";BeanPropertyRowMapper<Test2>  rowMapper=new BeanPropertyRowMapper<>(Test2.class);List<Test2> query=jdbcTemplate.query(sql,rowMapper,5);System.out.println(query);for(Test2 bean:query){System.out.println(bean);int id = bean.getId();System.out.println(id);}}