PHP's return syntax and semantics - php

Question

What's the difference between two function A,F? sorry for using mysql instead of mysqli or PDO
function A ($B){
if($result = mysql_query("SELECT C FROM D WHERE E"))
{
if ($row = mysql_fetch_array($result))
{
return $text = $row['C'];
}
return 0;
}
return 0;
}
and this one:
function F ($G){
if($result = mysql_query("SELECT C FROM D WHERE E"))
{
if ($row = mysql_fetch_array($result))
{
return $row['C'];
}
}
return 0;
}

Answer 1

The end result in both cases is the same (as they are now), since both functions will return the value of column C if queries are successful and return a result.
On the first example A will also return 0 if the query is successful but no results are returned hence if you modify it as:
function A ($B){
if($result = mysql_query("SELECT C FROM D WHERE E"))
{
if ($row = mysql_fetch_array($result))
{
return $text = $row['C'];
}
return 0;
}
return 1;
}
if the returned value is 0 you'll know the query was successfull but if the return value was 1 it will mean the query execution failed. That is if C does not contain the values 0 or 1 where in that case you wouldn't really be sure on whether the returned 0 or 1 is the return value of column C or the function's actual return statement
UPDATE
To distinguish between the two you could return false if something has failed:
return false;
and then check if the return value of the function is really false:
if(A() === false)
{
// something went wrong, do something else
}
Note: See the ===, it makes sure that the equality check only checks for boolean value false and that string "false" or values 0 or '0' are not classified as false