私は持っている
Array_A ( [0] => Array ( [DATE] => 2012-11-28 , [totalCount] => )
[1] => Array ( [DATE] => 2012-11-29 , [totalCount] => )
[2] => Array ( [DATE] => 2012-11-30 , [totalCount] => ) )
Array_B ( [10] => Array ( [DATE] => 2012-11-28 , [totalCount] => 30 )
[11] => Array ( [DATE] => 2012-11-30 , [totalCount] => 40 )
[12] => Array ( [DATE] => 2012-12-05 , [totalCount] => 50 ) )
Array_A を Array_B の値に置き換える必要があり、出力が
Array_A ( [0] => Array ( [DATE] => 2012-11-28 , [totalCount] => 30 )
[1] => Array ( [DATE] => 2012-11-29 , [totalCount] => )
[2] => Array ( [DATE] => 2012-11-30 , [totalCount] => 40 ) )