Sql server insert or update row

I already tried it, but unsuccessfully. See my edited post. From the MSDN documentation : Performs insert, update, or delete operations on a target table based on the results of a join with a source table. Adam Porad Adam Porad Edited my first post. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown.

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To guaranty that any number of concurrent transaction will succeed you MUST use a lock. Adding a lock allow this to happen in a very short time-frame, preventing an error. I always thought use locking hints are bad, and we should let Microsoft Internal engine dictate locks. Is this the apparent exception to the rule? Show 3 more comments. See my detailed answer to a very similar previous question Beau Crawford's is a good way in SQL and below, though if you're granting rep it should go to the first guy to SO it.

Now it's really just one IO operation, but awful code Community Bot 1 1 1 silver badge. Keith Keith k 69 69 gold badges silver badges bronze badges. Ian Boyd - yeah, that's the SQL standard's syntax, not the upsert that just about all the other DB providers decided to support instead. The upsert syntax is a far nicer way to do this, so at the very least MS should have supported it too - it's not like it's the only non standard keyword in T-SQL — Keith.

See here weblogs. According to the linked post, MERGE implicitly takes out an update lock, but releases it before inserting rows, which can cause a race condition and primary key violations on insert. Show 8 more comments. Beau Crawford Beau Crawford 1, 2 2 gold badges 10 10 silver badges 3 3 bronze badges. Primary key violations should not occur if you have the proper unique index constraints applied. The whole point of the constraint is to prevent duplicate rows from every happening. It doesn't matter how many threads are trying to insert, the database will serialize as necessary to enforce the constraint Of course, wrapping this in a serialized transaction would make this more correct and less susceptible to deadlocks or failed inserts.

Wrapping it in a serializable transaction is the correct way to prevent errors in the above set of statements. Even if you have a primary key that is a auto-increment, your concern will then be any unique constraints that might be on the table. What you are saying is that if update fails and another process gets there first with an insert your insert will fail. In that case you have a race condition anyway. Locking won't change the fact that the post-condition will be that one of the processes that tries writing will get the value.

END CATCH However, this is problematic if for no other reason than letting SQL Server catch exceptions that you could have prevented in the first place is much more expensive, except in the rare scenario where almost every insert fails.

Aaron Bertrand Aaron Bertrand k 36 36 gold badges silver badges bronze badges. Show 1 more comment. Edit: Alas, even to my own detriment, I must admit the solutions that do this without a select seem to be better since they accomplish the task with one less step.

Mitch Wheat k 42 42 gold badges silver badges bronze badges. Esteban Araya Esteban Araya I still like this one better. The upsert seems more like programming by side effect, and I have never seen the piddly little clustered index seek of that initial select to cause performance problems in a real database.

Eric Weilnau Eric Weilnau 5, 4 4 gold badges 30 30 silver badges 30 30 bronze badges. MERGE is susceptible to race conditions see weblogs.

EBarr - Thanks for the link on the locks. I have updated my answer to include the suggest locking hint. Also check out mssqltips.

Denver Denver 81 1 1 silver badge 1 1 bronze badge. RamenChef 5, 11 11 gold badges 29 29 silver badges 40 40 bronze badges. Daniel Acosta Daniel Acosta 71 1 1 silver badge 1 1 bronze badge. RamenChef I don't understand. Ask the user that wrote the post. Saleh Najar Saleh Najar 51 1 1 silver badge 2 2 bronze badges.

Kristen Kristen 4, 2 2 gold badges 27 27 silver badges 34 34 bronze badges. Interesting idea, but incorrect syntax.

I have never needed to use a cursor to do this with large datasets. You just need an update that updates the records that match and an insert with a select instead of a values clause that left joins to the table. Result: The "first" of the two treads to insert, decides value. Wanted result: The last of the 2 threads to write data update or insert should decide value But; in a multithreaded environment, the OS scheduler decides on the order of the thread execution - in the above scenario, where we have this race condition, it was the OS that decided on the sequence of execution.

Bo Persson If you just do an update then insert without any locking or elevated isolation, then two users could try to pass the same data back I wouldn't consider it a bug in the middle tier if two users tried to submit the exact same information at the same time - depends a lot on context, doesn't it?

They both enter the update, which returns 0 rows for both, then they both try to insert. A common table expression EmployeeTemp defines the rows from one or more tables to be inserted into the NewEmployee table.

The following example creates the table EmployeeSales and inserts the name and year-to-date sales data for the top 5 random employees from the table HumanResources. Employee in the AdventureWorks database. The following example specifies a view name as the target object; however, the new row is inserted in the underlying base table.

For more information, see Modify Data Through a View. The following example specifies a table variable as the target object in the AdventureWorks database. Examples in this section demonstrate how to insert rows into a remote target table by using a linked server or a rowset function to reference the remote table. The following example inserts rows into a remote table. The linked server name, MyLinkServer , is then specified as part of the four-part object name in the form server.

The linked server name created in the previous example is used in this example. First, create an external table that points to the destination file or directory.

For more information, see Get started with PolyBase. The following example creates a new table a heap and inserts data from another table into it using minimal logging. This ensures that the statement uses minimal space in the transaction log and performs efficiently. Examples in this section demonstrate how to use table hints to temporarily override the default behavior of the query optimizer when processing the INSERT statement.

Because the SQL Server query optimizer typically selects the best execution plan for a query, we recommend that hints be used only as a last resort by experienced developers and database administrators. The following example specifies that an exclusive X lock is taken on the Production.

These results can be returned to the processing application for use in such things as confirmation messages, archiving, and other such application requirements. ScrapReasonID column. Because these values are generated by the Database Engine during the insert operation, neither of these columns can be defined in MyTableVar.

It also deletes rows for products whose inventories drop to 0. The example captures the rows that are deleted and inserts them into another table, ZeroInventory , which tracks products with no inventory.

Skip to main content. This browser is no longer supported. Download Microsoft Edge More info. Contents Exit focus mode. Is this page helpful? Please rate your experience Yes No. Any additional feedback? Note Table value constructor is not supported in Azure Synapse Analytics.

Note Inserts into local temporary tables identified by the prefix and global temporary tables identified by prefixes are also enabled for parallelism using the TABLOCK hint.

Note The table vaule constructor is not supported in Azure Synapse Analytics. Caution Because the SQL Server query optimizer typically selects the best execution plan for a query, we recommend that hints be used only as a last resort by experienced developers and database administrators.

In this article. Remove trailing spaces to the last non-space character or to a single-space character for strings made up of only spaces. Specifying target objects other than standard tables.

Bulk loading data from tables or data files.