Fix erros php and cron job of website

I need an expert in php and MySQL for solve asap and urgently the follow problems, because all them work perfectly, but from days ago, all these stopped to work and i dont know why...: 1. The website does not search products in the searcher of front end when you write in searcher some word, give the follow error: Error Number: 1364 Field 'added_by' doesn't have a default value INSERT INTO `tbl_product_searches` (`search_keyword`, `user_id`, `matched_rows`) VALUES ('case', 0, 544537) Filename: /var/www/vhosts/[login to view URL] Line Number: 1296 2. It does not update the products of the web. The cron job that is scheduled does not work. When the cron job works correctly, it removes all the products on the web eachtime that cron job is running and inserts them again, because this eliminates obsolete products and inserts new ones. Also when the cron job works, it updates every day "the product of the day" and the "best offers". Is very important that when cron job is running no add more products above that already exist: -- first must remove all products and -- after reinsert the products existing in FTP 3. I have a fuction in admin panel, where you can upload a csv file and automatically it insert all coupons and deals in my web (first delete the coupons and deals existing, second insert all new), but now I can not upload the csv of coupons and deals in the admin panel, because it gives the follow error: Error Number: 1366 Incorrect integer value: '' for column 'discount_percent' at row 1 INSERT INTO `tbl_cp_tmp` (`type`, `title`, `discount_code`, `discount_percent`, `url`, `expiring_date`, `merchant_name`, `description`) VALUES (2, 'Extra $5 OFF for Blackview BV7000 Pro Smartphone, $184.99 free shipping(Code: BV7000PRO)', 'BV7000PRO', '', '[login to view URL]', '2017-03-23 00:00:00.0', 'TOMTOP Technology Co., Ltd', 'MTK6750T 64-bit Octa Core Android 6.0 5.0 Inches FHD 1920*1080Pixels Screen 8+13MP Camera 3500mAh OTG Smart Gesture HotKnot WiFi FM Radio E-compass Fingerprint') Filename: /var/www/vhosts/[login to view URL] Line Number: 111