变量mysql查询（其中$ variable = everything）

I am thinking about the most efficient way to make a function that returns the number of rows I get on a certain query. I need to have a lot of variations of the query as I use it for a lot of statistics.(in the real version it is about 5 variables, not 2) Instead of posting my full code I created a small snippet that will point out what I'm trying to overcome. $conn is my PDO connection. the name of the table as well as the names of the fields are fixed.

function stackOverflowDemo($var1,$var2){
global $conn;
$totalrows = $conn->query("select count(*) from $table WHERE firstfield = $var1 AND secondfield = $var2 ")->fetchColumn();
return $totalrows;
}

$output = stackOverflowDemo('1','30');

So right now it will give me the amount of rows who meet the above conditions. (firstfield = 1 AND secondfield = 30) but now comes the clue : now I want the number of rows where firstfield is 1 and secondfield is anything (like *). How can I make that work for me , without having to write a new function or a dedicated query ?

function stackOverflowDemo($var1,$var2){
global $conn;
$query = "select count(*) from $table WHERE firstfield IS $var1 AND secondfield IS $var2";
$totalrows = $conn->query($query)->fetchColumn();
return $totalrows;
}

$output = stackOverflowDemo('1','NOT NULL');

maybe this works for you?

now I want the number of rows where firstfield is 1 and secondfield is anything (like *)

Your query should find occurrences of each firstfield and secondfield separately and then count them.

Omitting null entries for secondfield, you can try the following:

select  
    sum(firstfield) first_field_count
  , sum(secondfield) second_field_count
from (
select
    case when firstfield=1 then 1 else 0 end as firstfield
  , case when secondfield is not null then 1 else 0 end as secondfield
from table_name
) t;