将同一表中一列的值更新到 SQL Server 中的另一列
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Update values from one column in same table to another in SQL Server
提问by Keven
I'm trying to overwrite values that are found in TYPE1 with values that are found in TYPE2.
我试图用在 TYPE2 中找到的值覆盖在 TYPE1 中找到的值。
I wrote this SQL to try it out, but for some reason it isn't updating:
我写了这个 SQL 来尝试一下，但由于某种原因它没有更新：
select * from stuff
update stuff
set TYPE1 = TYPE2
where TYPE1 is null;
update stuff
set TYPE1 = TYPE2
where TYPE1 ='Blank';
http://www.sqlfiddle.com/#!3/a4733/17
http://www.sqlfiddle.com/#!3/a4733/17
Any reason why my values in TYPE1 are not updating?
我在 TYPE1 中的值没有更新的任何原因？
回答by Sparky
This works for me
这对我有用
select * from stuff
update stuff
set TYPE1 = TYPE2
where TYPE1 is null;
update stuff
set TYPE1 = TYPE2
where TYPE1 ='Blank';
select * from stuff
回答by Bob Taylor
UPDATE a
SET a.column1 = b.column2
FROM myTable a
INNER JOIN myTable b
on a.myID = b.myID
in order for both "a" and "b" to work, both aliases must be defined
为了使“a”和“b”都能工作，必须定义两个别名
回答by Gy?ri Sándor
UPDATE TABLE_NAME SET COLUMN_A = COLUMN_B;
Much easier. At least on Oracle SQL, i don't know if this works on other dialects as well.
容易多了。至少在 Oracle SQL 上，我不知道这是否也适用于其他方言。
回答by Ahmed Mahmoud AbdElbaset
This answer about updating column from a part of another column in the same table.
这个关于从同一表中另一列的一部分更新列的答案。
update T1
set domainname = (New value) --Example: (SELECT LEFT(TableName.col, CHARINDEX('@',TableName.col)-1) STRIPPED_STRING FROM TableName where TableName.col = T2.Emp_ID)
from TableName T1
INNER JOIN
TableName T2
ON
T1.ID= T2.ID;
回答by Hyman
You put select query before update queries, so you just see initial data. Put select * from stuff;to the end of list.
您将选择查询放在更新查询之前，因此您只会看到初始数据。放在select * from stuff;列表的末尾。
回答by Ian Kenney
Your select statement was before the update statement see Updated fiddle
您的选择语句在更新语句之前，请参阅更新的小提琴
回答by Tarek.Iraqi
update TABLE_1 a set COLUMN_1 = (select COLUMN_2 from TABLE_1 b where a.ID = b.ID)
