Oracle update statement correlated subquery

You can use a database link to update a remote object only if you are using Oracle Database distributed functionality. If you omit dblink, then the database assumes the object is on the local database.

Regardless of its form, it must return a collection value—that is, a value whose type is nested table or varray. This process of extracting the elements of a collection is called collection unnesting. For example, you could roll up four quarterly sales tables into a yearly sales table.

Specify a correlation name alias for the table, view, or subquery to be referenced elsewhere in the statement. Specify the name of a column of the object that is to be updated. If column refers to a LOB object attribute, then you must first initialize it with a value of empty or null. You cannot update it with a literal. If column is part of the partitioning key of a partitioned table, then UPDATE will fail if you change a value in the column that would move the row to a different partition or subpartition, unless you enable row movement.

I keep getting the ORA Subquery returns more than one row. I was hoping to update several records at a time by joining the update table to the subquery. When I break down each section into select statements, I get the expected results. Below is the script I am using. In addition, a correlated subquery may be evaluated once for each row selected by the outer query. Because of this, a query that uses a correlated subquery could be slow. A correlated subquery is also known as a repeating subquery or a synchronized subquery.

The following query finds all products whose list price is above average for their category. Should I use dynamic sql cos the similar query will be written but for different tables. Answer: NO - static is faster than dynamic and list of tables is not likely to change.

However, the code would look a little ugly with similar updates for different tables. It seems that you imply that I should put the corelated subquery inside each update instead of running it once and running individual updates for each record, correct? September 05, - pm UTC. A reader, September 05, - pm UTC. I am having a little trouble writing this.

Thank you so much!! We can derive from this: a c is not meaningful So, we can create: drop table st; create table st a int primary key, b int ; drop table dt; create table dt a int ; drop table t1; create table t1 a int , b int primary key ; Now, all we need to do is join DT to ST by A.

That should work though I did not get a chance to test it out - I think the conditions that you said should be true are true - so I should be all set. Thanx again!!!! January 25, - am UTC. Dear sir, Thanks for your response. Sorry for disturbing you again. Any other ways to put the following query?

Do you some other ways? Please do reply. January 26, - am UTC. You want to use an explicit conversion in order to do what you are trying to do. You are relying on default date formats and the english language being in place. Neither of which is assured. You'll never be sorry. A reader, January 26, - am UTC. Tom, I took this code from above and pasted in vi so that i can generate insert statement.

January 26, - pm UTC. A reader, January 26, - pm UTC. I am trying to use this alternate update form Paul D. Phillips, March 19, - pm UTC. I am reading this with great interest, as I hate the need to go through a table twice to do one update, once to insure that a update value is there for the target row the one to be updated and then a second time to get the update value to apply to the target.

I am attempting to use this form of inline view, I think that is what it is, but am encountering an ORA error that I do not think I should be getting. I'm running 9. Doing DSS work through multi million row tables, one less pass represents an enourmous improvement. And, by the way, your previous help with analytic operators has proven to be a major productivity boost for me, also.

March 19, - pm UTC. Dear Sir, I tried the following queries. What's wrong over there? March 20, - am UTC. Dear Tom, Still the query doesn't work. But you forget to join them in the select statement.

Thats what Tom the great meant. Tom, I hate to seem like I'm beating this to death, here, but I really want to understand why this is not working.

I copied the code right off the page and pasted it into Worksheet, and both tried to run it and tried to Explain it and it shows the same thing both times. If both tables have Primary Keys, one with 2 columns and one with 3 and the one with the 3 has the 2 from the other table and a single value for the 3rd obviously , how is this not key preserved?

Simply put: from t1 a, t2 b where a. As for the key-preserved tables, I'm still working on understanding what this means too. I'm guessing that Oracle doesn't like the fact that you are joining on two columns of a three column composite key.

This is probably not a feasable workaround for you though. I'm guessing that Oracle doesn't consider the join to be key-preserved since joining on two columns of a three-column primary key won't necessarily produce a unique result. You took care of this by writing "AND m. I don't know if this is a bug or if it is intentional.

At any rate I wanted to let you know why the hint didn't work when you copied and pasted from the Followup. Good Luck! March 24, - am UTC. Wow, what a difference! Paul, March 24, - am UTC. Ed and Tom, when I fixed the hint, that did work, thank you both very much. The shocking thing is how much of an improvement this makes in the update.

I'm going to use this in selected cases, I think. I'm still debating whether to open a TAR, though. I think from Tom's statement this is the intended behaviour, though why a literal is not sufficient, but a join is, is a bit puzzling. I had to try You never know. How this hint can alter the execution plan of the Update Statement? Please do write a followup. Thanks in advance. April 13, - pm UTC. Stable set of rows Padders, April 27, - am UTC.

Not so sure about that. Also I stumbled on another way to do this which involves creating an unusable unique index on the join column s. This appears to work on 10g but not 9. Presumably this would be considered a bug?

I believe the below example illustrates all of the above. Personal Oracle Database 10g Release April 28, - pm UTC. Hence, I'm putting this one back into my list of "don't use". April 29, - am UTC. It might be possible to overcome the "randomness" of the BYPASS hint if we have some criteria for which of the source rows to use.