Re: update, insert ... gee.. a puzzle

2016/03/17 12:47 ... lejeczek:
> ..  that you experts I hope can crack like a digestive biscuit...
>
> how does one update, or merge or whatever is right technical term for it
> - a my.table from my.another table (both are schematically identical, no
> foreign keys, one primary key) but..
> does it a way so when there is a duplicate only NULLs in my.table get
> updated/replaced with proper values from my.another table?
>
> many thanks, specially for actual syntax hints.
Nothing here is easy....

My best is INSERT ... SELECT ... ON DUPLICATE KEY UPDATE ...;

INSERT INTO my.table SELECT * FROM my."another table" ON DUPLICATE KEY 
UPDATE /* every single field "f" not in the key thus: */ f = 
IFNULL(my.table.f, my."another table".f);

By the way, there always is only one primary key. Maybe you mean that 
there is only one field to it?

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