Question

我需要更新此表：

中心：

+-----+------------+---------+--------+
|  id |  country   | process | center |
+-----+------------+---------+--------+
|  1  |     1      |    1    |   1    |
|  2  |     1      |    2    |   1    |
|  3  |     1      |    3    |   1    |
|  4  |     2      |    1    |   1    |
|  5  |     2      |    2    |   1    |
|  6  |     2      |    3    |   1    |
|  7  |     3      |    1    |   1    |
|  8  |     3      |    2    |   1    |
|  9  |     3      |    3    |   1    |
+-----+------------+---------+--------+

在选择过程中，我检索了两个临时表：

TempCountries：

+-----+------------+
|  id |  country   |
+-----+------------+
|  1  |     1      |
|  2  |     3      |
+-----+------------+

和TempProcesses：

+-----+------------+
|  id |  process   |
+-----+------------+
|  1  |     2      |
|  2  |     3      |
+-----+------------+

在子查询中，我得到了所有可能的值组合：

SELECT TempCountries.countryId, TempProcesses.processesId FROM TempCenterCountries,TempCenterProcesses

这将返回：

+-----+------------+---------+
|  id |  country   | process |
+-----+------------+---------+
|  1  |     1      |    2    |
|  2  |     1      |    3    |
|  3  |     3      |    2    |
|  4  |     3      |    3    |
+-----+------------+---------+

在选择过程中，用户选择这些组合的中心。假设center = 7。现在，我需要更新存在子查询组合的“中心”表中的中心值。

所以

UPDATE Centers SET center = 7 WHERE ?

所以我得到了

+-----+------------+---------+--------+
|  id |  country   | process | center |
+-----+------------+---------+--------+
|  1  |     1      |    1    |   1    |
|  2  |     1      |    2    |   7    |
|  3  |     1      |    3    |   7    |
|  4  |     2      |    1    |   1    |
|  5  |     2      |    2    |   1    |
|  6  |     2      |    3    |   1    |
|  7  |     3      |    1    |   1    |
|  8  |     3      |    2    |   7    |
|  9  |     3      |    3    |   7    |
+-----+------------+---------+--------+

Answer 1

尝试使用此标准sql

Update Centers
set center = 7
where country in (select country from TempCenterCountries)
   and process in (select process from TempCenterProcesses)

Answer 2

并不是所有的sql实现都允许您在使用update时使用from子句。在您的情况下，幸运的是，由于要进行所有组合的笛卡尔乘积运算，这意味着在两个值之间没有任何约束。

UPDATE  Centers
SET center = 7
WHERE   country IN (SELECT countryId FROM TempCountries)
AND process IN (SELECT processId FROM TempCenterProcesses)

Answer 3

在运行更新查询之前，您需要准确匹配国家和流程。因此，类似下面的查询将帮助您实现这一目标。如果有记录，基本上更新列

WITH (SELECT TempCountries.countryId, TempProcesses.processesId
FROM TempCenterCountries,
 TempCenterProcesses) AS TempTables,
UPDATE Centers
SET center = 7
WHERE EXISTS (SELECT 1
          FROM TempTables tmp
          WHERE country = tmp.countryId and process = tmp.processesId
         );

想法是如果国家和流程都与您已经在临时表中获取的记录相匹配，则更新记录。

Answer 4

使用更新联接-

对于Sql Server

update c set SET center = 7 from Centers c
join
(SELECT TempCountries.countryId, TempProcesses.processesId FROM TempCenterCountries join TempCenterProcesses
)A on c.countryid=A.countryid and c.processesId=A.processId

对于Mysql-

    update Centers c  
    join
    (SELECT TempCountries.countryId, TempProcesses.processesId FROM TempCenterCountries join TempCenterProcesses
    )A on c.countryid=A.countryid and c.processesId=A.processId
    set SET center = 7

更新值对在SQL中匹配的位置

4 个答案: