使用PHP中另一个数组的值替换数组中的值

I have two arrays. Array 1 is a mapping between DeptID and dept_number:

array(66) {
[0] => array(2) {
 'DeptID' → str•4 '1300'
 'dept_number' → str•3 '18'
}

[1] => array(2) {
 'DeptID' → str•4 '1000'
 'dept_number' → str•3 '129'
}

[2] => array(2) {
 'DeptID' → str•4 '2400'
 'dept_number' → str•3 '101'
}

...and so on

Array 2 has store records which include dept_number. I want to replace the dept_number value with the DeptID value from Array 1.

array(27) {
[0] => array(11) {
 'org_id' → str•2 '11'
 'org_number' → str•2 '11'
 'supplier_number' → str•4 '3806'
 'supplier_name' → str•17 'TEST1'
 'invoice_number' → str•8 'DXXX'
 'receive_date' → str•10 '2013-09-11'
 'inv_status' → str•7 'Pending'
 'final_cost' → str•6 '317.30'
 'final_qty' → str•5 '12.00'
 'dept_number' → str•2 '18'
 'dept_descr' → str•10 'BULK 1'
}

[1] => array(11) {
 'org_id' → str•2 '11'
 'org_number' → str•2 '11'
 'supplier_number' → str•4 '1070'
 'supplier_name' → str•24 'TEST2'
 'invoice_number' → str•7 'DXXY'
 'receive_date' → str•10 '2013-09-11'
 'inv_status' → str•7 'Pending'
 'final_cost' → str•6 '830.30'
 'final_qty' → str•5 '26.00'
 'dept_number' → str•2 '101'
 'dept_descr' → str•10 'BULK 2'
}

...and so on

How do I replace the dept_number in Array 2 with the DeptID from Array 1?

Hash tables.

Start making a KVP (Key Value Pair) array of your mapping array with the key being whatever value you want to look up values for (in this case, dept_number) and set the value of the array key to DeptID:

$deptKVP = array();
foreach ($deptMappings as $deptMapping) {
    $deptKVP[$deptMapping['dept_number']] = $deptMapping['DeptID'];
}

/*
    $deptKVP = [
        18 => 1300,
        129 => 1000,
        101 => 2400
    ];
*/

And then simply iterate through your regular array:

foreach ($array2 as &$subArray) {
    $subArray['dept_number'] = $deptKVP[$subArray['dept_number']];
}
unset($subArray); //Unset the reference

If your dept_number is unique:

foreach ($array1 as $a1)
    $array3[ $a1['dept_number'] ] = $a1['DeptId'];

Now you have an associated array1 in array3. Next, iterate array2

foreach($array2 as $key=>$value)
    $array2[$key]['DeptId'] = $array3[ $value['dept_number'] ];

You're basically going to have to loop through Array 2, and check each dept_number value against each dept_number in Array 1:

foreach($array2 as $arr2_record){
    foreach($array1 as $arr1_record){
        if($arr2_record['dept_number'] == $arr1_record['dept_number']){
            $arr2_record['DeptID'] = $arr1_record['DeptID'];
            $arr2_record['dept_number'] = null;
        }
    }
}

EDIT: If you want to maintain the "dept_number" key, then you would just set the $arr2_record['dept_number'] to the "DeptID" of $arr1_record