Oracle insert or update statement

You can determine the number of rows that will be inserted by running the following Oracle SELECT statement before performing the insert. Question: I am setting up a database with clients. The use of the dual table allows you to enter your values in a select statement, even though the values are not currently stored in a table.

Based on the contacts and customers table, insert into the contacts table all customers who reside in the state of 'Florida'. Since the number of fields in the contacts and customers table are the same and the fields are listed in the same order, you could write the solution as follows though it is generally better practice to list the column names in case the table definitions change :. While using this site, you agree to have read and accepted our Terms of Service and Privacy Policy. Viewed k times.

The UPSERT operation either updates or inserts a row in a table, depending if the table already has a row that matches the data: if table t has a row exists that has key X: update t set mystuff Mark Harrison Mark Harrison k gold badges silver badges bronze badges. Add a comment. Active Oldest Votes. Apparently the "merge into" statement is not atomic. It can result in "ORA unique constraint" when used concurrently. The check for existence of a match and the insertion of a new record are not protected by a lock, so there is a race condition.

To do this reliably, you need to catch this exception and either re-run the merge or do a simple update instead. In Oracle 10, you can use the "log errors" clause to make it continue with the rest of the rows when an error occurs and log the offending row to another table, rather than just stopping.

Hi, I tried to use same query pattern in my query but somehow my query is inserting duplicate rows. I am not able to find more information about DUAL table. Shekhar Dual is a dummy table with a single row and columnn adp-gmbh. TimSylvester - Oracle uses transactions, so guarantees the snapshot of data at the start of a transaction is consistent throughout the transaction save any changes made within it. So, you'll never have a race condition if a constraint check is done before the insert regardless of how many concurrent calls are made to same SQL code.

Worst case, you may get lots of contention and Oracle will take much longer to reach a final state. RandyMagruder Is it the case that its and we still cannot do a upsert reliably in Oracle! Do you know of a concurrent safe solution? Show 7 more comments. Synesso I've come back here to check out this pattern again. It fails silently when concurrent inserts are attempted.

One insert takes effect, the second merge neither inserts or updates. However, the faster approach of doing two separate statements is safe. Too bad that with this pattern we need to write twice the data John, Smith NicolasBarbulesco this answer doesn't need to write the data twice: stackoverflow.

Tony Andrews Tony Andrews k 20 20 gold badges silver badges bronze badges. The issue is that you have a window in between the insert and the update where another process could successfully fire a delete.

I did however use this pattern on a table that never has deletes fired against it. OK, I agree. Don't know why it wasn't obvious to me. I disagree with Chotchki.

Brian Schmitt Brian Schmitt 5, 1 1 gold badge 23 23 silver badges 36 36 bronze badges. Your provided solution does not work for me.

What if the update returned 0 rows modified because the record was already there and the values were the same? Syntax Errors here : — ilmirons. Community Bot 1 1 1 silver badge. Evgeniy Berezovsky Evgeniy Berezovsky Finally, a concurrent accesses safe answer. Any way to use such a construct from a client eg. You mean not having to call a stored proc? Well, in that case you could also just catch the specific Java exceptions and retry in a Java loop.

I'm sorry: I was not specific enough. But you understood the right way. I resigned to do like you just said. It is not a good solution performance-wise. But my goal is to let the Java developers of my project use my method to upsert in any table I cannot create one PLSQL stored procedure per table, or one procedure per upsert type. I'm just not volunteering to figure it out for you Except when doing load testing of course