I want to update a field in table1 with another field in table2.I wrote the following query but it is not working.
UPDATE tempdata A
SET A.new_user_id =
(SELECT B.id FROM user B
WHERE A.usr_email = B.usr_email)
It is giving "#1242 - Subquery returns more than 1 row" error. Anybody please help me.
UPDATE tempdata A, user B
SET A.new_user_id = B.id
WHERE A.usr_email = B.usr_email
you can still join tables even if it is an update statement.
UPDATE tempdata A
INNER JOIN user B
ON A.usr_email = B.usr_email
SET A.new_user_id = B.id
Beware that error means that in table user there are more than 1 rows with field usr_email equals to tempdata's one. Check for dupes before runniing the actual update statement with the LIMIT 1 a suggested by Salil
This is also one way to handle this scenerio
UPDATE A
SET A.new_user_id = B.id
FROM tempdata A
INNER JOIN user B ON A.usr_email = B.usr_email
Related
I'm looking for a simple way to do an update on a table only if there is no other columns present in that same table with the same value I'm trying to update, ideally in a single query. So far I'm getting an error You specify target table 't1' for update in FROM clause. Here is what I tried in a few variations so far (still unable to get working):
UPDATE emailQueue AS t1
SET
t1.lockedOn = 1470053240
WHERE
(SELECT
COUNT(*)
FROM
emailQueue AS t2
WHERE
t2.lockedOn = 1470053240) = 0
AND t1.lockedOn IS NULL
In MySQL, you need to use a join. In this case, a left join is in order:
UPDATE emailQueue eq LEFT JOIN
emailQueue eq2
ON eq2.lockedOn = 1470053240
SET eq.lockedOn = 1470053240
WHERE eq.lockedOn IS NULL AND
eq2.lockedOn IS NULL;
I have: something like
UPDATE table
SET field = (SELECT field FROM another_table WHERE id = #id);
Problem: SELECT field FROM another_table WHERE id = #id subquery can return one field or EMPTY SET.
Question: How to handle situation when subquery returns empty set?
Updated:
UPDATE table t
SET field = IF((SELECT field FROM another_table WHERE id = #id) IS NOT NULL, -- select field
(SELECT field FROM another_table WHERE id = #id), -- Problem #1: select field AGAIN!
(SELECT field FROM table WHERE id = t.id) -- Problem #2: try to not change value, so select the current field value!!
);
If function can be useful:
UPDATE table
SET field = if((SELECT field FROM another_table WHERE id = #id) IS NULL,true,false);
You can add the conditional:
WHERE (SELECT COUNT(*) FROM another_table WHERE id = #id) > 0
This will make sure that at least one row exists in another_table with the id. See my SQL Fiddle as an example.
Note: this may not be the most efficient because it does a count on another_table, and if it is greater than 1 it will do another SELECT (two sub-queries). Instead, you can do an INNER JOIN:
UPDATE table
INNER JOIN another_table ON table.id=another_table.id
SET table.field = another_table.field
WHERE another_table.id = #id;
See this SQL Fiddle. The reason why I saved this as a second option, is not all SQL languages can UPDATE with joins (MySQL can). Also, you need some way to relate the tables..in this case I said that the table.id we are updating is equal to another_table.id we are taking the data from.
NOTE The UPDATE statement will modify EVERY row in table and assign the same value to every row; that seems a little unusual.
To answer your question:
If you want to handle the "empty set" by not updating any rows in table, then one way to do this is with a JOIN to an inline view:
UPDATE table t
CROSS
JOIN (SELECT a.field
FROM another_table a
WHERE a.id = #id
LIMIT 1
) s
SET t.field = s.field
Note that if the inline view query (aliased as s) return an "empty set", then no rows in table will be updated, because the JOIN operation will also return an "empty set", meaning there are zero rows to be updated.
Hi I want to update a table with the values of another but do not how to do it.
I have tried this but it is not working.
UPDATE tblagendamiento SET
CodigoAgenda =
(select tmptable.CodigoCita from tmptable where tmptable.id = tblagendamiento.id);
And this is the error:
Subquery returns more than 1 row
You are actually getting an error because your subquery is returning more than one row. I think you can achieve this simply using an INNER JOIN query
UPDATE tblagendamiento a
INNER JOIN tmptable b
ON a.id = b.id
SET a.CodigoAgenda = b.CodigoCita
The message is telling you that there is more than one row returned by your subquery. Assuming you don't want to use a random value (which you can do by appending limit 1 to the query), it means your where clause is not selective enough.
Is it possible to achieve next thing without using views, but just one single query? I have two tables:
TableA->TanbleB (1-many) ON TableA.Id = TableB.TableAId
I need to update one field in Table A (TableA.Field1) for records in TableA that satisfy condition on one field in tableA (WHERE TableA.Field2=SomeValue)
.
TableA.Field1 will be updated from TableB with value that is last inserted (last inserted value in related records to TableA).
I will put an example:
UPDATE TableA a SET Field1 = (SELECT TOP 1 b.Feild1 * b.Field2 FROM TableB b WHERE b.TableAId = a.id) WHERE field2 = 1
I know Above example doesn't work, but I have many ways tried using INNER JOIN and failed. I had an idea to use something like this:
UPDATE TableA INNDER JOIN ( SELECT ... FROM TABLE B) ON TABLEA.Id= TableB.TableAId SET ....
But the 2ns query should return 1 record for each DISTINCT TableAId, but only the last inserted.
I hope I am making some sense here.
Thanks in advance.
Here is some SQL that will do what you want
UPDATE T1 INNER JOIN T2 ON T1.ID = T2.T1ID SET T1.F2 = [T2].[F2]*[T2].[F3] WHERE (((T1.F1)="ABC") AND ((T2.ID)=DMax("[ID]","[T2]","[T1ID]=" & [T1].[ID])));
This predicated on T1.ID being the primary key for T1 and T2.T1ID being a index field in T2
One of the flaws in Access is that you can't run an "UPDATE" query based on a "SELECT" query, it will usually give the error:
Operation must use an updateable query
The only way around is as you say to create a view of the "SELECT" query and then inner join this on your table, Access is then working with a static recordset and can handle the "UPDATE" query ok
Alternatively you could write a VBA procedure to step through line by line with the Recordset.
Best of luck : )
UPDATE:
SELECT b.TableAId, b.Feild1 * b.Field2 INTO tblView FROM TableB As b WHERE b.field2 = 1
I am trying to make update statement in MySql table - just migrating data from one user to second user. The concrete row should be migrated only when the row with same unique ID devid doesn't exist yet for that second user.
The update statement that I used is:
update userdata as userdata1 set userid=${newuser}
where
userid=${olduser} and
userdata1.devid !=
(select devid from userdata as userdata2
where
userdata2.userid = ${newuser} and userdata2.`devid` = userdata1.`devid`)
The MySql returns:
You can't specify target table 'userdata' for update in FROM clause
But from the other way, similar select statement works, or similar update statement, when I test data on another that same table works as well. So that is this some limitation, that there is not possible to do select on same table during update? And how to manage this?
Thanks,
Jindrich
You can use a left join:
UPDATE userdata u1
LEFT JOIN userdata u2 ON u2.userid = :newuser AND u2.devid = u1.devid
SET u1.userid = :newuser
WHERE u1.userid = :olduser
AND u2.userid IS NULL;