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我对始终返回 ID= 1的 LEAD 感到困惑，它甚至不是表中的 ID（ID 从 ~18k 开始），而不是下一条记录的有效 ID。NULL 值是它们应该在的位置，它只是应该包含有效 ID 的行。具有相同语法的 LAG 按预期工作，返回正确的值。当我注释掉 LAG 时，LEAD 甚至不起作用（正确）。顺便说一句，我从我的其他脚本中复制了代码（并且只是更改了表和列名），它工作正常。

UPDATE PRJ SET 
    PrevJob = SRC.PrevID,  -- << write Previous ID
    NextJob = SRC.NextID   -- << write Next ID
FROM PRJ as PRJ
LEFT JOIN  (
      SELECT 
          ID,  -- << ID for joining to the original record
          LAG(ID)  OVER (PARTITION BY RPCode,PNInt ORDER BY OrderNo) AS PrevID, -- << previous works
          LEAD(ID) OVER (PARTITION BY RPCode,PNInt ORDER BY OrderNo) AS NextID  -- << next returns 1
      FROM PRJ as PRJ2 
      ) as SRC ON SRC.ID = PRJ.ID

这是使用 SELECT 的结果示例（请参阅最后一列中的 1 值）：

ID       PNInt       RPCode               OrderNo PrevJob              NextJob
-------- ----------- -------------------- ------- -------------------- -------
18783    53          00005320171113120000 1       NULL                 1
18795    53          00005320171113120000 2       18783                1
18789    53          00005320171113120000 3       18795                NULL
18784    53          00005320171127120000 1       NULL                 1
18796    53          00005320171127120000 2       18784                1
18790    53          00005320171127120000 3       18796                NULL
18785    53          00005320171211120000 1       NULL                 1
18797    53          00005320171211120000 2       18785                1
18791    53          00005320171211120000 3       18797                NULL
18786    53          00005320171225120000 1       NULL                 1
18798    53          00005320171225120000 2       18786                1
18792    53          00005320171225120000 3       18798                NULL
18787    53          00005320180108120000 1       NULL                 1
18799    53          00005320180108120000 2       18787                1
18793    53          00005320180108120000 3       18799                NULL

我担心这可能是我看不到的一些愚蠢的拼写错误。或者 LAG 和 LEAD 有什么问题吗？

4

2 回答 2

3

首先，您可以更简单地写成：

UPDATE toupdate
    SET PrevJob = SRC.PrevID,  -- << write Previous ID
        NextJob = SRC.NextID   -- << write Next ID
FROM (SELECT PRJ.*, 
             LAG(ID)  OVER (PARTITION BY RPCode, PNInt ORDER BY OrderNo) AS new_PrevID, -- << previous works
             LEAD(ID) OVER (PARTITION BY RPCode, PNInt ORDER BY OrderNo) AS new_NextID  -- << next returns 1
      FROM PRJ
     ) toupdate;

我无法解释你看到的行为。要检查的两件事：

  • id 字段的类型。
  • 可能在表上定义的任何触发器。
于 2017-11-20T12:07:28.530 回答
1

无法复制您的问题，请参阅此 SQL Fiddle

MS SQL Server 2014 架构设置：

CREATE TABLE PRJ
    ([ID] int, [PNInt] int, [RPCode] varchar(20), [OrderNo] int, [PrevJ] varchar(5), [NextJ] varchar(4))
;

INSERT INTO PRJ
    ([ID], [PNInt], [RPCode], [OrderNo], [PrevJ], [NextJ])
VALUES
    (18783, 53, 'O0005320171113120000', 1, NULL, '1'),
    (18795, 53, 'O0005320171113120000', 2, '18783', '1'),
    (18789, 53, 'O0005320171113120000', 3, '18795', NULL),
    (18784, 53, 'O0005320171127120000', 1, NULL, '1'),
    (18796, 53, 'O0005320171127120000', 2, '18784', '1'),
    (18790, 53, 'O0005320171127120000', 3, '18796', NULL),
    (18785, 53, 'O0005320171211120000', 1, NULL, '1'),
    (18797, 53, 'O0005320171211120000', 2, '18785', '1'),
    (18791, 53, 'O0005320171211120000', 3, '18797', NULL),
    (18786, 53, 'O0005320171225120000', 1, NULL, '1'),
    (18798, 53, 'O0005320171225120000', 2, '18786', '1'),
    (18792, 53, 'O0005320171225120000', 3, '18798', NULL),
    (18787, 53, 'O0005320180108120000', 1, NULL, '1'),
    (18799, 53, 'O0005320180108120000', 2, '18787', '1'),
    (18793, 53, 'O0005320180108120000', 3, '18799', NULL)
;

查询 1：

      SELECT 
          ID,  -- << ID for joining to the original record
          LAG(ID)  OVER (PARTITION BY RPCode,PNInt ORDER BY OrderNo) AS PrevID, -- << previous works
          LEAD(ID) OVER (PARTITION BY RPCode,PNInt ORDER BY OrderNo) AS NextID  -- << next returns 1
      FROM PRJ as PRJ2

结果：

|    ID | PrevID | NextID |
|-------|--------|--------|
| 18783 | (null) |  18795 |
| 18795 |  18783 |  18789 |
| 18789 |  18795 | (null) |
| 18784 | (null) |  18796 |
| 18796 |  18784 |  18790 |
| 18790 |  18796 | (null) |
| 18785 | (null) |  18797 |
| 18797 |  18785 |  18791 |
| 18791 |  18797 | (null) |
| 18786 | (null) |  18798 |
| 18798 |  18786 |  18792 |
| 18792 |  18798 | (null) |
| 18787 | (null) |  18799 |
| 18799 |  18787 |  18793 |
| 18793 |  18799 | (null) |
于 2017-11-20T11:03:50.317 回答