java mysql jdbcTemplate 使用

1.查询数量、ID int类型数据

    String sql = "select count(id) from ddd "
    int total= jdbcTemplate.queryForObject(sql,new Object[]{},Integer.class);
    
2.查询单条数据单个字段信息

    String sql = "select name from ly_store_user where id=?";
    try {
        String userInfo = jdbcTemplate.queryForObject(sql,new Object[]{user_id},String.class);
        System.out.println(userInfo);
        return userInfo;
    } catch (Exception e) {
        e.printStackTrace();
        return null;
    }
    
3.查询单条数据

    String sql = "select * from ly_store_user where username=?";
    try {
        StoreUser userInfo = jdbcTemplate.queryForObject(sql,new Object[]{username},new BeanPropertyRowMapper<StoreUser>(StoreUser.class));
        return userInfo;
    } catch (Exception e) {
      e.printStackTrace();
      return null;
    }
    
4.多条数据查询

    String sql = "select * from ly_store_user where id>10";

    // 有实体类
    List<StoreRecharge> list = jdbcTemplate.query(sql.toString(),new Object[]{},new BeanPropertyRowMapper<>(StoreRecharge.class));
    List<HashMap<String, Object>> listData = new ArrayList<HashMap<String, Object>>();
    for (StoreRecharge info : list) {
        HashMap<String, Object> map = new HashMap<String, Object>();
        String newTime = DateUtil.timeStamp2Date(info.getCreated_at(), "yyyy-MM-dd");
        map.put("money",info.getMoney());
        map.put("money_give",info.getMoney_give());
        map.put("status",info.getStatus());
        map.put("created_at",newTime);
        listData.add(map);
    }
    
    // 无实体类
    List<Map<String, Object>> list = jdbcTemplate.queryForList(sql);//查询结果为储存map元素的集合
    for (Map<String, Object> info : list) {
        String newTime = DateUtil.timeStamp2Date(info.get("created_at").toString(), "yyyy-MM-dd");
        info.put("created_at",newTime);
    }

本文地址：https://blog.csdn.net/gugu251/article/details/109001801