Update-Users-Manager.ps1

$adPath = 'LDAP://DC=contoso,DC=msft'
$objDomain = New-Object -TypeName System.DirectoryServices.DirectoryEntry -ArgumentList ($adPath)

$CSV = Import-Csv -Path file.csv
        
foreach($record in $CSV)
{
    $employeeFromRecord = $($record.employee).trim()
    $managerFromRecord = $($record.manager).trim()
            
    $ObjSearchEmployee = New-Object -TypeName System.DirectoryServices.DirectorySearcher -ArgumentList ($objDomain)
    $ObjSearchEmployee.Filter = "(&(objectCategory=person)(objectClass=user)(employeeID=$employeeFromRecord))"
    $allSearchResultEmployee = $ObjSearchEmployee.FindAll()
    
    $ObjSearchManager = New-Object -TypeName System.DirectoryServices.DirectorySearcher -ArgumentList ($objDomain)
    $ObjSearchManager.Filter = "(&(objectCategory=person)(objectClass=user)(sAMAccountname=$managerFromRecord))"
    $userManager = $ObjSearchManager.FindAll()
    
    $userManagerDN = $userManager.Properties.distinguishedname
    $userManagerDisplayname = $userManager.Properties.displayname

    foreach($result in $allSearchResultEmployee)
    {
        $user = [adsi]$result.path
        $userDisplayName = $user.displayName
        $user.put('manager',"$userManagerDN")
        $user.SetInfo()
        
        Write-Host -Object "$userManagerDisplayname is now the manager of $userDisplayName"
    }
}