Data Samples

SAMPLE [ BLOCK ] (sample_percent)  [ SEED (seed_value) ]

See the Select statement in the Oracle® SQL Reference for exceptions, refinements, and cautions regarding 'Block', 'Seed', etc.

SQL> Select Count(*) From Employees;

 COUNT(*)
----------
      107

 1  Select Employee_Id, First_Name, Last_Name
 2*   From Employees Sample(10);

EMPLOYEE_ID FIRST_NAME           LAST_NAME
----------- -------------------- --------------
        109 Daniel               Faviet
        112 Jose Manuel          Urman
        118 Guy                  Himuro
        119 Karen                Colmenares
        128 Steven               Markle
        136 Hazel                Philtanker
        148 Gerald               Cambrault
        170 Tayler               Fox

Since this is just an estimate, unless you specify a 'seed,' you will get a variation of counts returned:

  1* Select Count(*) From Employees Sample(10)
SQL> /
        15
SQL> /
        10
SQL> /
        11
SQL> /
        10
SQL> /
         9