如果在MySQL中为null，如何更新字段？

Question

我有一个名为size的字段。有些行是null。我想将这些行'size字段更新为0。我该怎么做？

Answer 1

update tablename
set    size = 0
where  size is null;

Answer 2

UPDATE TABLENAME
SET size = 0
WHERE size IS NULL

Answer 3

您必须在更新子句中使用WHERE size IS NULL：

UPDATE table SET size = 0 WHERE size IS NULL;

Answer 4

UPDATE TABLENAME 
SET SIZE=0
WHERE SIZE IS NULL;