如何通过根据条件添加“1”来更新列值？

Question

我有下表fields：

+----------+---------+-----------------+-------------+---------+--------------+---------------+-----------+------------------------------+-------------+------------------+
| field_id | form_id | form_section_id | is_required | grid_id | is_base_grid | field_type_id | field_seq |          field_name          | field_class | field_class_data |
+----------+---------+-----------------+-------------+---------+--------------+---------------+-----------+------------------------------+-------------+------------------+
|   220481 |    9926 | NULL            |           0 | NULL    | NULL         |             4 |        28 | Test                         | NULL        | NULL             |
|   281863 |    9926 | NULL            |           0 | NULL    | NULL         |            10 |        29 | insert after yes no question | NULL        | NULL             |
|   220496 |    9926 | NULL            |           0 | 11      | 1            |             5 |        30 | test                         | NULL        | NULL             |
|   249234 |    9926 | NULL            |           0 | 12      | 1            |             5 |        32 |                              | NULL        | NULL             |
|   279877 |    9926 | NULL            |           0 | NULL    | NULL         |             4 |        33 | Test Text Questions          | NULL        | NULL             |
|   281860 |    9926 | NULL            |           0 | NULL    | NULL         |            10 |        34 | Something                    | NULL        | NULL             |
|   281914 |    9926 | NULL            |           0 | 23      | 1            |             5 |        35 | sssss                        | NULL        | NULL             |
|   281960 |    9926 | NULL            |           0 | 38      | 1            |             5 |        36 | yuyuyu                       | NULL        | NULL             |
|   281972 |    9926 | NULL            |           0 | 40      | 1            |             5 |        40 | ttttt                        | NULL        | NULL             |
+----------+---------+-----------------+-------------+---------+--------------+---------------+-----------+------------------------------+-------------+------------------+

正如您所看到的，在这种情况下有两个field_seq具有相同的值36。

假设我正在插入一个新行，field_id=281960而field_seq这样的新行的36.

我需要构建一个查询甚至一个存储过程，我可以在其中找出是否存在field_seq等于或大于的行，36如果是，则将 的值更新field_seq为当前值 plus 1。

前任：

INSERT INTO `fields` VALUES(9999, 9926, NULL, 0, 41, 1, 5, 36, 'lllll', NULL, NULL);

有了这个，请参阅下面的可能案例（每个案例后面都有示例）：

情况 1： field_seq=36 的行已经存在于表中

• 保持 INSERT 数据原样，它将成为当前的field_seq=36新行
• 更新表行的值，该值field_seq=current+1将变为37
• 如果37已经存在则重复上一步直到不再重复field_seq

前：

+----------+---------+-----------------+-------------+---------+--------------+---------------+-----------+-------------+-------------+------------------+
| field_id | form_id | form_section_id | is_required | grid_id | is_base_grid | field_type_id | field_seq | field_nanme | field_class | field_class_data |
+----------+---------+-----------------+-------------+---------+--------------+---------------+-----------+-------------+-------------+------------------+
|   281914 |    9926 | NULL            |           0 |      23 |            1 |             5 |        32 | sssss       | NULL        | NULL             |
|   281972 |    9926 | NULL            |           0 |      40 |            1 |             5 |        36 | ttttt       | NULL        | NULL             |
|   281960 |    9926 | NULL            |           0 |      38 |            1 |             5 |        37 | yuyuyu      | NULL        | NULL             |
|   281978 |    9926 | NULL            |           0 |      38 |            1 |             5 |        38 | vvvvv       | NULL        | NULL             |
+----------+---------+-----------------+-------------+---------+--------------+---------------+-----------+-------------+-------------+------------------+

后：

+----------+---------+-----------------+-------------+---------+--------------+---------------+-----------+---------------------+-------------+------------------+
| field_id | form_id | form_section_id | is_required | grid_id | is_base_grid | field_type_id | field_seq |     field_nanme     | field_class | field_class_data |
+----------+---------+-----------------+-------------+---------+--------------+---------------+-----------+---------------------+-------------+------------------+
|   281914 |    9926 | NULL            |           0 | 23      | 1            |             5 |        32 | sssss               | NULL        | NULL             |
|     9999 |    9926 | NULL            |           0 |    41   |   1          |             5 |        36 | lllll               | NULL        | NULL             | => new row inserted here
|   281972 |    9926 | NULL            |           0 | 40      | 1            |             5 |        37 | ttttt               | NULL        | NULL             | => this was 36 now is updated to 37
|   281960 |    9926 | NULL            |           0 | 38      | 1            |             5 |        38 | yuyuyu              | NULL        | NULL             | => this was 37 now is updated to 38
|   281978 |    9926 | NULL            |           0 | 38      | 1            |             5 |        39 | vvvvv               | NULL        | NULL             | => this was 38 now is updated to 39
|   220524 |    9926 | NULL            |           0 | NULL    | NULL         |             5 |        40 | Patient Information | NULL        | NULL             | => we don't care about this cause there is room for one more, if one insert makes the rows above become 40 then this needs to be updated to 41
+----------+---------+-----------------+-------------+---------+--------------+---------------+-----------+---------------------+-------------+------------------+

情况 2： field_seq=36 的行已经存在于表中，但 nextfield_seq大于37

• 保持 INSERT 数据原样，它将成为当前的field_seq=36新行
• 更新表行的值，该值field_seq=current+1将变为37
• 在这种情况下，我们不需要继续更新，因为有足够的空间在它们变得相同之前再插入几行 field_seq

前：

+----------+---------+-----------------+-------------+---------+---------------+---------------+-----------+------------+-------------+
| field_id | form_id | form_section_id | is_required | grid_id | is_base_grid  | field_type_id | field_seq | field_name | field_class |
+----------+---------+-----------------+-------------+---------+---------------+---------------+-----------+------------+-------------+
|   281914 |    9926 | NULL            |           0 |      23 |             1 |             5 |        32 | sssss      | NULL        |
|   281972 |    9926 | NULL            |           0 |      40 |             1 |             5 |        36 | ttttt      | NULL        |
|   281972 |    9926 | NULL            |           0 |      40 |             1 |             5 |        40 | ooooo      | NULL        |
+----------+---------+-----------------+-------------+---------+---------------+---------------+-----------+------------+-------------+

后：

+----------+---------+-----------------+-------------+---------+---------------+---------------+-----------+------------+-------------+
| field_id | form_id | form_section_id | is_required | grid_id | is_base_grid  | field_type_id | field_seq | field_name | field_class |
+----------+---------+-----------------+-------------+---------+---------------+---------------+-----------+------------+-------------+
|   281914 |    9926 | NULL            |           0 |      23 |             1 |             5 |        32 | sssss      | NULL        |
|   281972 |    9926 | NULL            |           0 |      41 |             1 |             5 |        36 | lllll      | NULL        | => new row inserted here
|   281972 |    9926 | NULL            |           0 |      40 |             1 |             5 |        37 | ttttt      | NULL        | => previous row with field_seq=36 was updated to 37
|   281972 |    9926 | NULL            |           0 |      40 |             1 |             5 |        40 | ooooo      | NULL        | => nothing happen to this one since there is room for more
+----------+---------+-----------------+-------------+---------+---------------+---------------+-----------+------------+-------------+

我使用的是 Microsoft SQL Server 2016 (SP1)。我怎么能做到这一点？

Answer 1

你可以尝试一下：

--enter procedure with insert parameters
DECLARE @field_seq INT = 36
DECLARE @field_seq_range INT

IF EXISTS(SELECT * FROM fields WHERE field_seq = @field_seq)
  BEGIN
    SELECT  @field_seq_range = MIN(f.field_seq)
    FROM    (
        SELECT  field_seq, LEAD(field_seq, 1, NULL) OVER (ORDER BY field_seq) next_field_seq
        FROM    fields
    ) f
    WHERE   f.field_seq >= @field_seq
    AND f.field_seq + 1 < f.next_field_seq

    UPDATE  f
    SET f.field_seq = f.field_seq + 1
    FROM    fields f
    WHERE   f.field_seq BETWEEN @field_seq AND @field_seq_range
  END

--perform insert

该代码将检查是否存在冲突，field_seq.如果存在，它将扫描表以查找下一个间隙，更新field_seq该范围内的所有值，并留下一个间隙来插入新记录。如果没有发现冲突，则跳过更新。不过，我无法对此性能做出任何保证。我确信有更优化的方法可以做到这一点。

这是dbfiddle - 您可以看到更新发生之前和之后，为插入创建了一个间隙。