query returns different results when executed using get_results()

Question

I have an SQL query that I'm running using WordPress default DB function get_results like so

$result = $wpdb->get_results("SELECT *, 'cash' AS mop 
          FROM wp_wpsp_cash_transactions 
          WHERE 1=1 AND DATE(date_time) > 2018-10-07 UNION ALL 
          SELECT *, 'bank' AS mop FROM wp_wpsp_bank_transactions
          WHERE 1=1 AND DATE(date_time) > 2018-10-07 ORDER BY date_time DESC")

The query is returning wrong results(I think its ignoring the date_time in WHERE clause). However, When I'm running this same query manually in phpmyadmin. The same query gives the correct result. I don't know what's happening here.

Answer 1

You should wrap date literal with ' :

SELECT *, 'cash' AS mop 
FROM wp_wpsp_cash_transactions 
WHERE 1=1 AND DATE(date_time) > '2018-10-07'  -- comparing with date not int
UNION ALL 
SELECT *, 'bank' AS mop 
FROM wp_wpsp_bank_transactions 
WHERE 1=1 AND DATE(date_time) > '2018-10-07'
ORDER BY date_time DESC;

Reason:

SELECT 1
WHERE NOW() > '2019-10-07'
-- 0 rows

SELECT 1
WHERE NOW() > 2019-10-07  -- implicit conversion
-- 1