Teradata SQL：将随机数据插入表中进行测试

Question

I am trying to create random data and insert it into a table. Right now just thinking what'd be the efficient approaches to get this done. eg

Create  volatile table mytb , no fallback, no journal
( C1 integer not null
  C2 Varchar (50) Not null , 
  C3 D1 Date Not null, 
  C4 D2 date not null 
) with data primary index ( c1) on commit preserve rows; 

What I want is to insert value randomly for X iterations for a specific List or range of each column value . eg C1 range is between 30 and 3000000 C2 is a list with ( 'approved','pending','unknown','disputed','wip','processed','pre-processed','denied' ) etc C3 is a date between 01-01-1999 to 12-31-2015 etc Then for say 1 million iterations I'd like to insert random values for these columns and CREATE a SKEW for certain values- that is there should be abundance of these values vs the rest. Has someone had a dig at this before . What the best way to do it - recursive Q logic ?

Answer 1

I use RANDOM to produce test data:

SELECT
   RANDOM(30,3000000) AS c1,
   CASE RANDOM(1,8) 
      WHEN 1 THEN 'approved'
      WHEN 2 THEN 'pending'
      WHEN 3 THEN 'unknown'
      WHEN 4 THEN 'disputed'
      WHEN 5 THEN 'wip'
      WHEN 6 THEN 'processed'
      WHEN 7 THEN 'pre-processed'
      WHEN 8 THEN 'denied'
   END,
   DATE '1999-01-01' + RANDOM(0,6208) -- up to 2015-12-31
FROM sys_calendar.CALENDAR -- any table with a large number of rows

This results in evenly distributed data, if you want skew you can run different insert/selects or play around with multiple RANDOMs:

RANDOM(1,50) + RANDOM(0,50)
(RANDOM(1, 50) * RANDOM(1,200) + RANDOM(0,100)) / 100.00