sql - selecting a row using MIN or ROWNUM -

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i have oracle table similar 1 below stores people's lastname firstname , age. if last name same people belong same family.

   lastname   firstname  age    =========================== 1   miller     charls     20 2   miller     john       30 3   anderson   peter      45 4   bates      andy       50 5   anderson   gary       60 6   williams   mark       15

i need write oracle sql query select youngest person each family. output shd select rows 1,3,4 , 6

how do ?

dense_rank() ranking function generates sequential number , ties number generated same. prefer use dense_rank() here considering family can have twins, etc.

select  lastname, firstname, age             (             select  lastname, firstname, age,                     dense_rank() on (partition lastname order age) rn                tablename         )   a.rn = 1

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