In fact, the query is using a temp table and filesort anyway, so this is still not achieving the once-through goal. This gets worse as you go to higher numbers top 3, top 4…. Because the grouping is on three columns, and the index is only on two. . It prevents the server sorting the results to eliminate duplicates before returning them.
I am not saying that your approach is bad. What I want to get is the highest score from the table and the name of the player. You can't delete your own topics. Otherwise system will generate error. Because this selects a , this only works if you are running with , which I hope you are not doing without good reason. What happens if two people decide to create a new Employee at similar times? Aggregate functions and subqueries are not permitted.
You can't post or upload images. Object, ByVal e As System. This syntax is optimized for Oracle and may not work for other database technologies. Since the first query is grouped, it needs to be put into a subquery so it can be joined against the non-grouped table: select f. I need a query that will return the customer who has ordered the highest total amount.
You can't vote in polls. You need to make sure that you are refining your query results to only return employees from department 30. Everybody look what's going down. Lets go into your code. If I go there I've played enough Diablo to know how to fight my way out. If this is a one time shot it's not a big deal, but if this is code going into a production environment, you should know that the performance speed of those two solutions may differ considerably at different volumes.
But if you need the last bit of speed out of your server, you sometimes have to know when to break the rules. You can't edit your own topics. Think this might do it. Close End Try That is a very, very bad idea. It did what I wanted, without a filesort or temporary table. Finding the first several from each group is not possible with that method because aggregate functions only return a single value.
You can't delete your own events. Since we have two class in our table so the sql command has returned two class with highest mark in each of them. Frequently Asked Questions Question: I'm trying to pull some info out of a table. For example, you might wish to know the maximum salary of all employees. This topic is related to numbering rows, which I just wrote about see my articles about and to assign a number to each row in a group.
Answer: This is where things get a bit complicated. You can't edit your own posts. Can it be done with one pass through the data, instead of the many passes required by a correlated subquery? You can't edit your own events. Question: I'm trying to get the employee with the maximum salary from department 30, but I need to display the employee's full information. We can define some header like this also. There are hacks and tweaks on every platform, and people who need to use them. If I go there I've played enough Diablo to know how to fight my way out.
Everybody look what's going down. Another linear-time technique, which might be a good option in cases where you are selecting most of the rows from the table anyway, is user variables. Return Types Returns a value same as expression. You can't post topic replies. Name MinSalary MaxSalary AvgSalary EmployeesPerDept ----------------------------- --------------------- --------------------- --------------------- ---------------- Document Control 10. Question: I'm trying to retrieve some info from an Oracle database. Take a look at and you'll see all three techniques compared.
One common solution is a so-called self-join. Simple example The following example returns the highest maximum tax rate in the AdventureWorks2012 database. You can't delete other events. To avoid that practice, we need to rephrase the problem and deep dive into it. You can't edit other topics. Each time a report is run in Oracle, a record is written to this table noting the above info.