Aggregate function
In database management an aggregate function is a function where the values of multiple rows are grouped together to form a single value of more significant meaning or measurement such as a set, a bag or a list.
Common aggregate functions include :
- Average() (i.e., arithmetic mean)
- Count()
- Maximum()
- nanmean() (mean ignoring NaN values, also known as "nil" or "null")
- Median()
- Minimum()
- Mode()
- Sum()
The listagg function, as defined in the SQL:2016 standard [1]
aggregates data from multiple rows into a single concatenated string.
Aggregate functions occur commonly in numerous programming languages, in spreadsheets, and in relational algebra.
See also
- Cross-tabulation a.k.a. Contingency table
- Data drilling
- Data mining
- Data processing
- Drill down
- Extract, transform, load
- Fold (higher-order function)
- Group by (SQL), SQL clause
- OLAP cube
- Online analytical processing
- Pivot table
- Relational algebra
- Utility functions on indivisible goods#Aggregates of utility functions
- XML for Analysis
References
https://msdn.microsoft.com/en-IN/library/ms173454.aspx
- ↑
Winand, Markus (2017-05-15). "Big News in Databases: New SQL Standard, Cloud Wars, and ACIDRain (Spring 2017)". DZone. Retrieved 2017-06-10.
In December 2016, ISO released a new version of the SQL standard. It introduces new features such as row pattern matching, listagg, date and time formatting, and JSON support.
Further reading
- Grabisch, Michel; Marichal, Jean-Luc; Mesiar, Radko; Pap, Endre (2009). Aggregation functions. Encyclopedia of Mathematics and its Applications. 127. Cambridge: Cambridge University Press. ISBN 978-0-521-51926-7. Zbl 1196.00002.
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