mnesia 简单查询

方法1：

F = fun () ->

MatchHead = #person{name='$1', sex=male, age='$2', _='_'},
Guard = [{'>', '$2', 30}],
Result = ['$1'],
mnesia:select(Tab,[{MatchHead, Guard, Result}])

end ,

mnesia:transaction(F).

方法二

MatchHead = #person{name='$1', sex=male, age='$2', _='_'},  % 也可包含等于条件   name=Name
Guard = [{'>', '$2', 30}], %条件 > == <
Result = ['$1'],  %结果  '$n'返回变量$n；'$$'返回所有  $变量；  '$_'返回整行；
mnesia:dirty_select(Tab,[{MatchHead, Guard, Result}]).