本文介绍了如果MySQL中的字段为null,则返回0的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
在MySQL中,是否可以将总计"字段设置为零(如果它们为NULL)?
In MySQL, is there a way to set the "total" fields to zero if they are NULL?
这就是我所拥有的:
SELECT uo.order_id, uo.order_total, uo.order_status, (SELECT SUM(uop.price * uop.qty) FROM uc_order_products uop WHERE uo.order_id = uop.order_id ) AS products_subtotal, (SELECT SUM(upr.amount) FROM uc_payment_receipts upr WHERE uo.order_id = upr.order_id ) AS payment_received, (SELECT SUM(uoli.amount) FROM uc_order_line_items uoli WHERE uo.order_id = uoli.order_id ) AS line_item_subtotal FROM uc_orders uo WHERE uo.order_status NOT IN ("future", "canceled") AND uo.uid = 4172;数据正常,除了NULL字段应为0.
The data comes out fine, except the NULL fields should be 0.
如何在MySQL中为NULL返回0?
How can I return 0 for NULL in MySQL?
推荐答案使用 IFNULL :
IFNULL(expr1, 0)从文档中:
如果expr1不为NULL,则IFNULL()返回expr1;否则返回expr2. IFNULL()返回数字或字符串值,具体取决于使用它的上下文.
If expr1 is not NULL, IFNULL() returns expr1; otherwise it returns expr2. IFNULL() returns a numeric or string value, depending on the context in which it is used.
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如果MySQL中的字段为null,则返回0
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