How to solve the error 'SUBQUERY CAN RETURN SINGLE VALUE'

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I am updating:

SQL

UPDATE table1 A SET (A.COLUMN_NAME) = (SELECT 1 FROM table2 WHERE A.COLUMN <> B.COLUMN)

But it throws an error

SUBQUERY CAN RETURN SINGLE VALUE

Please suggest how to update.

Posted 26-Sep-14 23:01pm

naveenece9

Updated 26-Sep-14 23:27pm

George Jonsson

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George Jonsson 27-Sep-14 5:29am

I updated your question.
Don't put the whole question in the title and don't use all capital letters.
It is shouting, and quite impolite.

George Jonsson 27-Sep-14 5:29am

And I am not sure your error message is correct.

Jörgen Andersson 27-Sep-14 5:35am

Before we can suggest how to update you need to elaborate on what you want to achieve.
Also state what database engine you're using.

naveenece9 27-Sep-14 5:57am

oracle

I want to update 1 from subquery when condition is <>. Please suggest if you can

Jörgen Andersson 27-Sep-14 6:10am

As George already questioned, is your error message correct?
Your update needs a subquery that's returning exactly one row per row to update.
Not equals will return all rows that fits the condition.
Do you have any IDs that can identify a single row?

[no name] 27-Sep-14 5:43am

And one more: there is no alias for B....ok, I assume that it should be table2. And then...your sub query gives most probably more then an row as a result..
Finally too many (or is it much...) would, could

naveenece9 27-Sep-14 5:51am

hello Bruno..

I want to update 1 from subquery when condition is <>. Please suggest if you can

[no name] 27-Sep-14 6:12am

Without knowing all the details you should change your update statement to something like:

UPDATE table1 A SET A.COLUMN_NAME = '1' WHERE EXISTS (SELECT B.COLUMN FROM table2 B WHERE A.COLUMN <> B.COLUMN)

naveenece9 27-Sep-14 6:43am

when I am updating max(1) then it is taking too much time for update

[no name] 27-Sep-14 6:47am

Why max(1) and not EXISTS? ....give me some minutes, I think to remember this Situation :)
Meanwhile check whether your indices are ok to serve optimal response time ;)

Bernhard Hiller 29-Sep-14 3:06am

First: get the correct values by your subquery. Currently it returns nonsense.
What do you expect it to return?
Next, combine the queries to a useful update query.

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Tim Carmichael · Answer 1 · 2014-09-27T00:09:00

As has been suggested, the subquery,

SELECT 1 FROM table2 WHERE A.COLUMN <> B.COLUMN

, is probably returning more than 1 row. So, there is more than 1 row where A.COLUMN <> B.COLUMN.

If you want a single value returned, change the subquery.

If possible, try to run the subquery by itself to see what it is returning.