如何比较从两个不同的提取数组中检索到的值

Question

I have two fetch arrays retrieved from the database, and try to compare two values until they have the matching, but it seems bit hard to figure out where I got wrong.

the two database have upto 2 jobrequestnumber so, the number of the matching is supposedly two, but it only counts one(indicated below).

 $value1=array();
 $value2 =array();

 $queryfordispatch = "select jobrequestnumber from dispatch";
 $resultfordispatch = mysql_query($queryfordispatch);
 $valuefordispatch =mysql_fetch_array($resultfordispatch);
 $value1 = $valuefordispatch['jobrequestnumber'];

 $queryforjobrequest = "select jobrequestnumber from jobrequest";
 $resultforjobrequest = mysql_query($queryfordispatch);
 $valueforjobrequest =mysql_fetch_array($resultforjobrequest);
 $value2 = $valueforjobrequest['jobrequestnumber'];

 $cfd=count($valuefordispatch);
 $cfj=count($valueforjobrequest);

//In this for loop, if I try to echo the value of $value1, it only produce the value of "1"

for($i=1; $i<=$cfd; $i++){
for($j=1; $j<=$cfj; $j++){
if ($value1 == $value2 ){

    $queryforupdate ="UPDATE jobrequest SET status = 'processed' where jobrequestnumber = $value2 ";
    mysql_query($queryforupdate);
  }
 }
}

So the result that I expect is that

jobnum

 1=1? yes --> update
 1=2? no  --> discard
 2=1? no  --> discard
 2=2? yes --> update

Answer 1

If you 're trying to see if array1 and array2 share values then use something like this.

$a = array('1','2','3','4','5','6','7','8','9');
$b = array('A','B','C','4','5','6','7','E','F');
$num_shared = 0;

foreach($a as $key => $val) {
    if (in_array($val, $b)) {
        echo $val . '<br />';
        $num_shared++;
    }
}

echo '<strong>'. $num_shared . '</strong>';

Answer 2

Let's start with this:

Welcome to Stack Overflow! Please, don't use mysql_* functions in new code . They are no longer maintained and are officially deprecated . See the red box ? Learn about prepared statements instead, and use PDO or MySQLi - this article will help you decide which. If you choose PDO, here is a good tutorial .

As for finding the difference between two arrays, one can always use array_diff :

 <?php //Example #1 array_diff() example $array1 = array("a" => "green", "red", "blue", "red"); $array2 = array("b" => "green", "yellow", "red"); $result = array_diff($array1, $array2); print_r($result); ?> 

Multiple occurrences in $array1 are all treated the same way. This will output:

 Array ( [1] => blue ) 

However, to compare each value separately, you need to loop through both arrays at the same time (with a for loop, preferably), and compare each and every item. Which is kind of what you're already doing.