Here ( is some info on the C implementation of the setting.
Updating multiple blogs at once
Additionally, It should seem obvious that you can also update from other tables as well.
In this case, the update doubles as a "SELECT" statement, giving you the data from the table you are specifying.
You are explicitly stating in your query the update values so, the second table is unaffected.
In this blog post, I am going to help you discover the "Update Filtered Issues at Once" feature and how you can make use of it to make your work simpler.
Before the "Update Filtered Issues at Once" feature was introduced, users have to manually modify each issue entry whenever they want to make updates.
With this feature, users can make changes to multiple issues in one go.
You can find the button to do this in three places - Find Issues page, My Issues panel as well as the Show Issue page for updating parent and child issues in one go.
If there is no duplicates then i dont want that row to be inserted. because i am fetching information from another site which maintains tables with id's. if the site has new records then i will end up inserting only the ids and count except all other information.
if and only if there is an entry for the id then it should update else it should skip. variant, a variant with "case / when / then" clause and a naive approach with transaction. The overall conclusion is that the variant with case statement turns out to be twice as fast as two other variants, but it's quite hard to write correct and injection-safe code for it, so I personally stick to the simplest approach: using transactions.
There is a setting you can alter called 'multi statement' that disables My SQL's 'safety mechanism' implemented to prevent (more than one) injection command.
Typical to My SQL's 'brilliant' implementation, it also prevents user from doing efficient queries.