Update where value pair matches in SQL - sql

Question

I need to update this table:
Centers:
+-----+------------+---------+--------+
| 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 |
+-----+------------+---------+--------+
During a selection process I retrieve two tempTables:
TempCountries:
+-----+------------+
| id | country |
+-----+------------+
| 1 | 1 |
| 2 | 3 |
+-----+------------+
And TempProcesses:
+-----+------------+
| id | process |
+-----+------------+
| 1 | 2 |
| 2 | 3 |
+-----+------------+
In a subquery I get all possible combinations of the values:
SELECT TempCountries.countryId, TempProcesses.processesId FROM TempCenterCountries,TempCenterProcesses
This returns:
+-----+------------+---------+
| id | country | process |
+-----+------------+---------+
| 1 | 1 | 2 |
| 2 | 1 | 3 |
| 3 | 3 | 2 |
| 4 | 3 | 3 |
+-----+------------+---------+
During the selection process the user chooses a center for these combinations. Let’s say center = 7.
Now I need to update the center value in the Centers table where the combinations of the subquery are present.
So,
UPDATE Centers SET center = 7 WHERE ?
So I get:
+-----+------------+---------+--------+
| 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

Not all sql implementations let you have a from clause when using update. Fortunately in your case since you're doing a Cartesian product to get all the combinations it implies that you don't have any constraints between the two values.
UPDATE Centers
SET center = 7
WHERE country IN (SELECT countryId FROM TempCountries)
AND process IN (SELECT processId FROM TempCenterProcesses)

Answer 2

Try if this standard sql,
Update Centers
set center = 7
where country in (select country from TempCenterCountries)
and process in (select process from TempCenterProcesses)

Answer 3

You need to have exact match of country as well as process before you run the update query. So, something like below query would help you achieve that. Basically update the column if there exists a record
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
);
The idea is to update the record if both country and process matches with the one you have already fetched in temporary table.

Answer 4

Use update join -
For 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
For 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