How to Replace NULL Fields with Zeros in a MySQL Query?

Set Null Fields to Zero in MySQL

This MySQL query aims to retrieve data from various tables, including the uc_orders (uo) table. However, the results contain null fields, which are desired to be returned as zero instead.

To achieve this, the IFNULL function can be employed within the subqueries:

SELECT uo.order_id,
       IFNULL(uo.order_total, 0) AS order_total,
       uo.order_status,
       IFNULL((SELECT SUM(uop.price * uop.qty)
                 FROM uc_order_products uop
                 WHERE uo.order_id = uop.order_id), 0) AS products_subtotal,
       IFNULL((SELECT SUM(upr.amount)
                 FROM uc_payment_receipts upr
                 WHERE uo.order_id = upr.order_id), 0) AS payment_received,
       IFNULL((SELECT SUM(uoli.amount)
                 FROM uc_order_line_items uoli
                 WHERE uo.order_id = uoli.order_id), 0) AS line_item_subtotal
FROM uc_orders uo
WHERE uo.order_status NOT IN ("future", "canceled")
AND uo.uid = 4172;

The IFNULL function essentially checks if the expression being evaluated is null. If it is, the specified fallback value (0 in this case) is returned instead. This ensures that the query will always return zero for null fields.

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