Question

我在SQlite中有以下表格：

_id | token | status | timestamp | mood | eta | name | calc_eta __________________________________________________________________________ 168 | iqmC.3aHMBGbl | ok | 1516625084498 | 50 | -4154 |样本名称| 1516625533082 169 | iqmC.3aHMBGbl | ok | 1516625084498 | 50 | -4214 |样本名称| 1516625533108 170 | iqmC.3aHMBGbl | ok | 1516625084498 | 50 | -4274 |样本名称| 1516625533414 171 | iqmC.3aHMBGbl | ok | 1516625084498 | 50 | -4334 |样本名称| 1516625533160 172 | iqmC.3aHMBGbl | ok | 1516625084498 | 50 | -4394 |样本名称| 1516625533680 173 | iqmC.3aHMBGbl | ok | 1516625084498 | 50 | -4420 |样品名称| 1516625533068 174 | iqmC.3aHMBGbl | ok | 1516625084498 | 50 | -4428 |样本名称| 1516625533482 175 | iqmC.3aHMBGbl | ok | 1516625084498 | 50 | -4483 |样品名称| 1516625533155 176 | iqmC.3aHMBGbl | ok | 1516625084498 | 50 | -4543 |样本名称| 1516625533148 177 | TFbintkHMBw4H | ok | 1516630122485 | 50 | 2526 |样品名称| 1516632672019 178 | TFbintkHMBw4H | ok | 1516630122485 | 50 | 2520 |样品名称| 1516632671903 179 | TFbintkHMBw4H | ok | 1516630122485 | 50 | 2460 |样品名称| 1516632672321 180 | TFbintkHMBw4H | ok | 1516630122485 | 50 | 2344 |样本名称| 1516632672859 181 | TFbintkHMBw4H | ok | 1516630122485 | 50 | 2336 |样本名称| 1516632671939 182 | TFbintkHMBw4H | ok | 1516630122485 | 50 | 2281 |样本名称| 1516632672802 183 | TFbintkHMBw4H | ok | 1516630122485 | 50 | 2220 |样本名称| 1516632671828 184 | TFbintkHMBw4H | ok | 1516630122485 | 50 | 2161 |样本名称| 1516632672625

我正在尝试提出一个查询，它会给我两个最新的（基于自动增量 _id ）， calc_eta 值之间的区别对于每个不同的令牌值。

所以在这种情况下结果应该是：

iqmC.3aHMBGbl | -7

TFbintkHMBw4H | 797

我使用SQL得到了这么多，但它目前没有提供每个不同令牌的计算值，我不确定如何进一步。

SELECT DISTINCT token,

  (SELECT calc_eta
   FROM DATA s
   WHERE
       (SELECT count(*)
        FROM DATA f
        WHERE f.token = s.token
          AND f._id >= s._id) <= 1) -
  (SELECT calc_eta
   FROM
     (SELECT calc_eta,
             MIN(_id)
      FROM DATA s
      WHERE
          (SELECT count(*)
           FROM DATA f
           WHERE f.token = s.token
             AND f._id >= s._id) <= 2)) AS delay
FROM DATA;

Answer 1

在大多数SQL方言中，您可以使用lag()：

等窗口函数

select d.*,
       (calc_eta - prev_calc_eta) as diff
from (select d.*,
             lag(calc_eta) over (partition by token order by _id) as prev_calc_eta,
             row_number() over (partition by token order by _id desc) as seqnum
      from data d
     ) d
where seqnum = 1;

返回SELECT DISTINCT查询

1 个答案: