Mediaspace scheduled maintenance: Aug 25, 2026 07:00 - 12:00 AM. During this time, videos will be temporarily unavailable. Check status updates.

Lecture

Aggregation Request and Result Sorting

Description

This lecture covers the main aggregation functions for statistical calculations on data sets or subsets, including grouping clauses to extract statistical values per data group. It also explains how to filter group queries using HAVING queries to extract the most relevant elements. Additionally, it demonstrates how to use sorting functions with the ORDER BY keyword and limit the number of objects displayed in a result.

In MOOC

Geographical Information Systems 1

Official source

Related concepts (9)

Sorting

Sorting refers to ordering data in an increasing or decreasing manner according to some linear relationship among the data items. ordering: arranging items in a sequence ordered by some criterion; categorizing: grouping items with similar properties. Ordering items is the combination of categorizing them based on equivalent order, and ordering the categories themselves. In , arranging in an ordered sequence is called "sorting". Sorting is a common operation in many applications, and efficient algorithms have been developed to perform it.

Sorting algorithm

In computer science, a sorting algorithm is an algorithm that puts elements of a list into an order. The most frequently used orders are numerical order and lexicographical order, and either ascending or descending. Efficient sorting is important for optimizing the efficiency of other algorithms (such as search and merge algorithms) that require input data to be in sorted lists. Sorting is also often useful for canonicalizing data and for producing human-readable output.

Sorting network

In computer science, comparator networks are abstract devices built up of a fixed number of "wires", carrying values, and comparator modules that connect pairs of wires, swapping the values on the wires if they are not in a desired order. Such networks are typically designed to perform sorting on fixed numbers of values, in which case they are called sorting networks. Sorting networks differ from general comparison sorts in that they are not capable of handling arbitrarily large inputs, and in that their sequence of comparisons is set in advance, regardless of the outcome of previous comparisons.

External sorting

External sorting is a class of sorting algorithms that can handle massive amounts of data. External sorting is required when the data being sorted do not fit into the main memory of a computing device (usually RAM) and instead they must reside in the slower external memory, usually a disk drive. Thus, external sorting algorithms are external memory algorithms and thus applicable in the external memory model of computation. External sorting algorithms generally fall into two types, distribution sorting, which resembles quicksort, and external merge sort, which resembles merge sort.

Bucket sort

Bucket sort, or bin sort, is a sorting algorithm that works by distributing the elements of an array into a number of buckets. Each bucket is then sorted individually, either using a different sorting algorithm, or by recursively applying the bucket sorting algorithm. It is a distribution sort, a generalization of pigeonhole sort that allows multiple keys per bucket, and is a cousin of radix sort in the most-to-least significant digit flavor. Bucket sort can be implemented with comparisons and therefore can also be considered a comparison sort algorithm.

Related lectures (30)

Merge Sort: Sorting Algorithm

Explains the merge sort algorithm, its correctness, and time complexity compared to other sorting algorithms.

Optimization Algorithms: Greedy Approach

Explores optimization problems and greedy algorithms for efficient decision-making.

Aggregation queries and sorting MOOC: Geographical Information Systems 1

Covers aggregation queries and sorting of results in Geographic Information Systems.

Introduction to Algorithms: Course Overview and Basics

Introduces the CS-250 Algorithms course, covering its structure, objectives, and key topics in algorithmic problem-solving.

Sorting Algorithms: Selection and Insertion