MySQL: Select odd row by if-statement

Question

I've a short MySQL-Query on my website:

...

for($i=0;$i<$sql->getRows();$i++) {
    $id = $sql->getValue("id");
    $name = $sql->getValue("name");
}

Is there a way to get every odd-row (every second row!) inside the query by an if-statement?

e.g.

for($i=0;$i<$sql->getRows();$i++) {
    $id = $sql->getValue("id");
    $name = $sql->getValue("name");

    if(ROW = ODD) {
        // DO SOMETING
    } else {
        // DO SOMETING ELSE
    }
}

Possible duplicate of [php test if number is odd or even](http://stackoverflow.com/questions/7959247/php-test-if-number-is-odd-or-even) — imtheman, Mar 21 '17 at 23:49
Your code does not seem to make much sense. I would assume a method called `getRows()` would get all the resultset from a query, but you are not processing a result array — RiggsFolly, Mar 22 '17 at 00:16

Jason Joslin · Answer 1 · 2017-03-22T01:36:41.800

0

Assuming an odd number is a digit that cannot return a whole number when it is divided by 2 you can try something like this:

/**
 * 
 * @param int $rowNumber
 * @return bool event number
 */
function isEven($rowNumber){
    $r = $rowNumber/2;
    return ctype_digit((string) $r);  
}

for($i=0;$i<$sql->getRows();$i++){

    if(isEven($i)){
        //do even code access the rowdata with ro
    }
    else{
        //do odd code
    }    
}

ctype_digit() will return true if all characters in a string are numeric. If it is an odd number the result will contain a decimal point and therefore return false.

As per @DrKey comment, he is right, a cleaner isEven function would look like

/**
 * 
 * @param int $rowNumber
 * @return bool event number
 */
function isEven($rowNumber){
    return $rowNumber % 2 == 0;
}

edited Mar 22 '17 at 01:36

answered Mar 22 '17 at 00:05

Jason Joslin

1,154
8
23

2

You are incrementing `$i` two times per row and `isEven` function can simply be `return $rowNumber % 2 == 0`. – DrKey Mar 22 '17 at 00:11
Ahh yeah my bad i orginally had it in a foreach loop so was manually doing the increment. when i changed it back to a for loop i forgot to remove that increment – Jason Joslin Mar 22 '17 at 00:14

MySQL: Select odd row by if-statement

1 Answers1