What is the difference between update and delete command?
The UPDATE command is to modify the existing records in the database. The DELETE command is used to delete the records in the database which are no longer required in the database.
What is the difference between delete query and update query?
Why do we use UPSERT?
Upsert is a combination of the words Update and Insert. With this method, existing records are updated and new records are inserted. Use of this method avoids creating unwanted duplicate records.
Which is better delete or insert in SQL Server?
Ie. person=123 has 200 rows to delete, but only 199 to insert. Update would not be able to handle this. Your best approach should be to use a MERGE statement and a table valued parameter with the new values. Of course, no ORM can handle this, but you mention ‘performance’, and the terms ‘performance’ and ‘ORM’ cannot be used in the same sentence…
How does SQL update do a delete then insert?
Partial-update transaction directly writes a character string at a user-defined position of a table column without issuing a delete and replace command, as would happen in a full update. Partial update does not support multibyte character set conversion. Partial update support is restricted to Microsoft SQL Server.
Which is faster update or delete or insert?
Delete + Insert is almost always faster because an Update has way more steps involved. Look for the row using PK. Read the row from disk. Mark rows as deleted (Only in the PK). Insert new rows at the end of the table. Update PK Index with locations of new records. (This doesn’t repeat, all can be perfomed in a single block of operation).
Which is faster to update or delete in SQL?
There are some scenarios involving bulk updates of all the rows in a table where it is faster to create a new table using CTAS from the old table (applying the update in the the projection of the SELECT clause), dropping the old table and renaming the new table.
https://www.youtube.com/watch?v=QAjXhJBZXdE