Updating multiple records sql qatar saudi arabia dating and friends
Code can be found here which is based on answer from @Dakusan Transaction: 5.5194580554962 Insert: 0.20669293403625 Case: 16.474853992462 Multi: 0.0412278175354 As you can see, multiple statements query is more efficient than the highest answer.
UPDATE summary_data SET current_category = (SELECT category_id FROM products WHERE products.product_id = summary_data.product_id) WHERE EXISTS (SELECT category_id FROM products WHERE products.product_id = summary_data.product_id); If you want to test your skills using the SQL UPDATE statement, try some of our practice exercises.
These exercises allow you to try out your skills with the UPDATE statement.
You will be given questions that you need to solve.
UPDATE table SET Col1 = 1 WHERE id = 1; UPDATE table SET Col1 = 2 WHERE id = 2; UPDATE table SET Col2 = 3 WHERE id = 3; UPDATE table SET Col1 = 10 WHERE id = 4; UPDATE table SET Col2 = 12 WHERE id = 4; 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.
So in general, I feel the INSERT method is both best and easiest to use.After each exercise, we provide the solution so you can check your answer. I have a SQLite database with table my Table and columns id, pos X, pos Y.The queries are smaller and easier to read and only take up 1 query of action. Bonus stuff: The solution for the INSERT non-default-field problem is to temporarily turn off the relevant SQL modes: first if you plan on reverting it. SQL files to remove php interpreter overhead 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.As for other comments I've seen that say the auto_increment goes up using the INSERT method, I tested that too and it seems to not be the case. Typical to My SQL's 'brilliant' implementation, it also prevents user from doing efficient queries.
Here ( is some info on the C implementation of the setting.