一列的SQL设置值等于同一表中另一列的SQL设置值 [英] SQL set values of one column equal to values of another column in the same table
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问题描述
我有一个包含两个DATETIME列的表.
I have a table with two DATETIME columns.
其中之一永远不会为NULL,但其中之一有时为NULL.
One of them is never NULL, but one of them is sometimes NULL.
我需要编写一个查询,将B列的所有NULL行设置为等于A列中的值.
I need to write a query which will set all the NULL rows for column B equal to the values in column A.
I have tried this example but the SQL in the selected answer does not execute because MySQL Workbench doesn't seem to like the FROM in the UPDATE.
推荐答案
听起来像您在一张桌子上工作,类似这样:
Sounds like you're working in just one table so something like this:
update your_table
set B = A
where B is null
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