Problem in use of json_encode?

I insert data with json_encode() in database, now i want get(select * from <table> ...) only name_unitsin of database? i want output this-> salam & mokhles & fadat

In database row units:

[{"name_units":"salam","price_units":"74,554","checkbox_units":["minibar","mobleman"]},
 {"name_units":"mokhles","price_units":"4,851,269","checkbox_units":["mobleman","tv"]},
 {"name_units":"fadat","price_units":"85,642","checkbox_units":["minibar","mobleman","tv"]}]

.

$query_hotel_search = $this->db->query("SELECT * FROM hotel_submits WHERE name LIKE '%$hotel_search%' ORDER BY name asc");
$data = array();
foreach ($query_hotel_search->result() as $row)
{
   $units = json_decode(开发者_如何学编程$row->units);
   $data[] = array('name' => $row->name, 'units' =>$units['name_units']); // Line 24
}
echo json_encode($data);

This is output above code:

A PHP Error was encountered

Severity: Notice

Message: Undefined index: name_units

Line Number: 24

[{"name":"Jack","units":null}]

You're getting an array of stdClass objects as a result from json_decode, rather than an associative array as you'd expect. It looks like you've got an array of JSON strings located in the same cell of your DB.

Assuming that's how your DB table is structure, if you want to output

salam & mokhles & fadat

then try this:

foreach( $query_hotel_search->result() as $row ) {
    $units = json_decode( $row->units );
    $names = '';
    foreach( $units as $unit ) {
        $names .= "{$unit->name_units} & ";
    }
}
echo substr( $names, 0, -2 );