SAMPLEID Expression | SQL SELECT Statements | Teradata Vantage - SAMPLEID Expression - Analytics Database - Teradata Vantage

SQL Data Manipulation Language

Deployment
VantageCloud
VantageCore
Edition
Enterprise
IntelliFlex
VMware
Product
Analytics Database
Teradata Vantage
Release Number
17.20
Published
June 2022
Language
English (United States)
Last Update
2024-04-05
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lifecycle
latest
Product Category
Teradata Vantage™

Identifies the sample to which a row belongs, distinguishing rows belonging to different samples specified in the SAMPLE clause of a SELECT statement.

ANSI Compliance

SAMPLEID is a Teradata extension to the ANSI SQL:2011 standard.

Definition of a Sample ID

The sample ID identifies the sample to which a row belongs in the left-to-right order of the SAMPLE clause specification, from 1 through n (where n is the number of samples requested in the SAMPLE clause).

Rules and Restrictions for SAMPLEID

The rules and restrictions are:
  • You can only specify SAMPLEID with a SAMPLE clause, which can appear either as part of a select list or as an ORDER BY clause expression.
  • SAMPLEID cannot be the only term specified in the select list. If you specify SAMPLEID, you must also specify at least one other non-SAMPLEID column expression.

Using SAMPLEID With Stratified Sampling

The SAMPLEID value for stratified sampling is simply 1, 2, 3, … n across n specified samples regardless of stratification. That is, for the following SAMPLE clause,

 
SAMPLE WHEN state = 'CA' THEN
0.3,
0.2
ELSE
0.5,
0.2
the SAMPLEID correspondence would be: 1 2   3 4