DESCRIBE Function | Teradata Vantage - 17.10 - DESCRIBE - Advanced SQL Engine - Teradata Database

Teradata Vantageā„¢ - Time Series Tables and Operations

Product
Advanced SQL Engine
Teradata Database
Release Number
17.10
Release Date
July 2021
Content Type
Programming Reference
Publication ID
B035-1208-171K
Language
English (United States)

Expands the SELECT list with aggregates of value_expression over time. DESCRIBE includes both fully parallel and single-threaded (when using VERBOSE) functions.

To invoke the time series version of this function, use the GROUP BY TIME clause. For more information, see GROUP BY TIME Clause.

Return Value

The return value is defined by each aggregate function that is actually invoked.

Nulls are not included in the result computation.

DISTINCT is not used with MODE when DESCRIBE VERBOSE is expanded.

The following functions are included in the result set of DESCRIBE:
  • MAX
  • MIN
  • AVERAGE
  • STDDEV_SAMP
If using the optional VERBOSE keyword, the list of aggregates also includes:
  • MEDIAN
  • MODE
  • 25th PERCENTILE
  • 50th PERCENTILE
  • 75th PERCENTILE

Additional aggregates included with VERBOSE are single-threaded, and require longer processing times. PERCENTILE computations use a linear process to determine if the percentile lies between two data points. VERBOSE includes MODE, which returns duplicate rows with different values.

The HAVING clause references any aggregates included as part of the DESCRIBE function.

Usage Notes

DESCRIBE has the following restrictions:
  • It can only be used in the SELECT list.
  • It cannot be used in comparisons.
  • It cannot be aliased.
  • It cannot be used as an argument to a function.

value_expression must be a numeric data type.