Usage-1
It returns a rows randomly from Teradata database.
Syntax for SAMPLE function:
SAMPLE [WITH REPLACEMENT]
[RANDOMIZED ALLOCATION]
[WHEN THEN]
{ | }
[…, | ]
[ELSE { |
It returns a rows randomly from Teradata database.
Syntax for SAMPLE function:
SAMPLE [WITH REPLACEMENT]
[RANDOMIZED ALLOCATION]
[WHEN
{
[…,
[ELSE {
Usage 2
It allows the user to get absolute number of rows or Percentage of rows.
Usage 3
It also allows the rows to get from multiple samples
How to get random rows from a table:
SELECT * from sample_table
SAMPLE 5;
How to get certain percentage of rows:
SELECT * from sample_table
SAMPLE .30;
How to get multiple SAMPLE data from a single tables with out duplicates:
SELECT * from sample_table
SAMPLE .20, SAMPLE .30
ORDER BY 1,2;
SQL query to get 3 samples with duplicates: So 'WITH REPLACEMENT" you will get duplicate rows:
SELECT ST_ID
,CC_ID
,SSID
FROM sample_table
SAMPLE WITH REPLACEMENT 8, 8, 8
ORDER BY 3, 1, 2 ;
What is percentage calculation in SAMPLE:
Total rows present in a tables/Percentage given in SQL query
Ex:
Total rows: 100
Percentage: 0.5
Therefore" 100/.5= 100/(5/10x100): 2 rows
This post first appeared on SriniTera - Data Analysis Solutions, please read the originial post: here
