将列插入 table 并将行递增 1

Question

给出以下 tables，我试图将 eventid 设置为最高值，递增 1。所以max(eventid) + 1。我似乎无法获得正确的 SQL 语法来完成此操作。

我现在拥有的有效但不能满足我需要的是以下内容。在这种情况下，如何让 eventid 显示 96740？

INSERT INTO stock_history
            (lastmodby,
             event,
             previous_stock,
             new_stock,
             lastmodified,
             productid)
SELECT '160'                     AS lastmodby,
       'SALE'                    AS event,
       stockstatus               AS previous_stock,
       stockstatus + 1           AS new_stock,
       Getdate()                 AS lastmodified,
       products_joined.productid AS productid
FROM   products_joined
WHERE  productcode = 'abc'

stock_history table

+--------+-----------+----------------+-------+-----------+-------+---------+-----------------------+-----------+
|   id   | productid | previous_stock | count | new_stock | event | eventid |     lastmodified      | lastmodby |
+--------+-----------+----------------+-------+-----------+-------+---------+-----------------------+-----------+
| 105619 |      9282 |              9 |     1 |        10 | SALE  |         | 7/24/2015 5:29:00 PM  |       160 |
| 105578 |      9282 |              8 |     1 |         9 | ORDER |   96739 | 7/23/2015 7:30:00 PM  |     37655 |
|  89241 |      9282 |              7 |     1 |         8 | ORDER |   96738 | 6/1/2014 6:06:00 PM   |     30761 |
|  86773 |      9282 |              6 |     1 |         7 | ORDER |   96737 | 4/12/2014 4:36:00 PM  |     29745 |
|  70419 |      9282 |              5 |     1 |         6 | ORDER |   96736 | 5/21/2013 1:17:00 PM  |      1754 |
|  69088 |      9200 |             19 |     1 |        20 | EDIT  |   96735 | 4/28/2013 10:26:00 AM |      1754 |
|  69050 |      9200 |             18 |     1 |        19 | ORDER |   96734 | 4/27/2013 2:17:00 PM  |     23001 |
|  68127 |      9200 |             17 |     1 |        18 | ORDER |   96733 | 4/13/2013 12:34:00 PM |     22674 |
|  67064 |      9200 |             16 |     1 |        17 | ORDER |   96732 | 3/30/2013 9:23:00 AM  |     22327 |
+--------+-----------+----------------+-------+-----------+-------+---------+-----------------------+-----------+

products_joined table

+-------------+-----------+-------------+
| productcode | productid | stockstatus |
+-------------+-----------+-------------+
| abc         |      9282 |           9 |
| xyz         |      9200 |          19 |
+-------------+-----------+-------------+

Answer 1

你最好使用 IDENTITY 列 - SQL 服务器会比你更有效地处理这个很多，无论是在性能方面还是在可靠性。 This question 为您提供了一些选项，例如

ALTER TABLE stock_history DROP COLUMN eventid
ALTER TABLE stock_history ADD eventid INT IDENTITY(1,1)

也就是说，技术上可以在查询中执行此操作。在 IDENTITY 列不是一个选项的情况下，了解此模式可能会有所帮助。

INSERT INTO stock_history
            (lastmodby,
             event,
             previous_stock,
             new_stock,
             lastmodified,
             productid,
             eventid)
SELECT '160'                     AS lastmodby,
       'SALE'                    AS event,
       stockstatus               AS previous_stock,
       stockstatus + 1           AS new_stock,
       Getdate()                 AS lastmodified,
       products_joined.productid AS productid,
       (SELECT MAX(eventid) + 1 FROM stock_history) AS eventid
FROM   products_joined
WHERE  productcode = 'abc'

请注意，如果此查询一次执行多次，这可能会导致重复 eventids。

将列插入 table 并将行递增 1

Insert column into table and increment row by one

sql

sql-server

insert

max