UPDATE如果column不为null，如果为null则保留为null

Question

我有以下SQL：

UPDATE TableA
SET first_name = 'AAA',
    last_name = 'BBB',
    address1 = '123',
    address2 = 'Fake St.,',
    phone = '1234567',
    id = '11223344'

如果每列都不为空，我应该使用什么才能更新？

Answer 1

update tableA
set first_name = case when first_name is null then null else 'aaa' end,
last_name = case when last_name is null then null else 'bbb' end,
...

Answer 2

另一种不那么冗长（不太可读）的方法：

UPDATE TableA
SET first_name = left(  'AAA' + first_name, 3 )  ,
    last_name = left(  'BBB' + last_name, 3 )  ,
    address1 = left(  '123' + address1, 3 )  ,
    address2 = left(  'Fake St.,' + address2, len( 'Fake St.,' ) )  ,
    ...