[PHP]Jak zmienić klucze i zredukować tablice Opcje

[silverwind]

[PHP] pobierz, plaintext 
 tab=[
  0 => [
    "createDate" => "2011-01-01 00:00:00"
  ]
  1 => [
    "createDate" => "2011-01-01 00:00:00"
  ]
  2 =>  [
    "createDate" => "2012-01-01 00:00:00"
  ]
  3 =>  [
    "createDate" => "2012-01-01 12:12:12"
  ]
  4 =>  [
    "createDate" => "2011-01-01 00:00:00"
  ]
  5 =>  [
    "createDate" => "2011-01-01 00:00:00"
  ]
]
[PHP] pobierz, plaintext 

jak przekształcić taką tablicę na

[PHP] pobierz, plaintext 
tab= [
  0 => "2011-01-01 2011-12-3"
  1 => "2011-01-01 2013-12-3"
  2 => "2012-01-01 12:12:12"
  3 => "2012-01-01 12:12:12"
  4 => "2011-01-01 12:12:12"
 5 => "2011-01-01 12:12:12"
]
[PHP] pobierz, plaintext