$clients = Clients::find()->select('id')->where(['not', ['chat | For Programming

$clients = Clients::find()->select('id')->where(['not', ['chat_id' => null]]);
SELECT `id` FROM `clients` WHERE NOT (`chat_id` IS NULL)
SELECT `id` FROM `clients` WHERE `chat_id` IS NOT NULL

hammasi bir hil natija beradi yani chat_id ni null emasligiga tekshiradi