[英]Updating mysql table field only when condition is met
我有這個查詢:
UPDATE orders SET tracking = '$trackingnumber', tracking_timestamp = NOW()
WHERE comment like '%$ordernumber%'
如果該字段的值是0000-00-00 00:00:00,是否可以僅更新tracking_timestamp?
您可以使用CASE
UPDATE orders
SET tracking = '$trackingnumber',
tracking_timestamp = CASE
WHEN tracking_timestamp='0000-00-00 00:00:00'
THEN NOW()
ELSE tracking_timestamp
END
WHERE comment like '%$ordernumber%'
使用此查詢
UPDATE orders
SET tracking = '$trackingnumber',
tracking_timestamp = IF (tracking_timestamp='0000-00-00 00:00:00',NOW(),'0000-00-00 00:00:00')
WHERE COMMENT LIKE '%$ordernumber%'
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