SQL 脚本根据其他列值更新列值

Question

I am new to writing SQL scripts and I am using SQL Server.

I have a table of data:

As you can see some of the race_title_short values are NULL. I want to update the values in this column based on the race_identifier_code .

For example one of the race_identifier codes is CORL which has a race_title_short of Coral Cup.

One of the records has the race identified as CORL but has no race_title_short .

How do I update the NULL race_title_short based on the race_identifier_code which have race title shorts in?

Answer 1

You can use a correlated subquery:

update t
    set race_title_short = (select max(t2.race_title_short)
                            from t t2
                            where t2.race_identifier_code = t.race_identifier_code
                           )
    where race_title_short is null;

Answer 2

With a self join:

update t
set t.race_title_short = tt.race_title_short
from tablename t inner join tablename tt
on tt.race_identifier_code = t.race_identifier_code
where t.race_title_short is null and tt.race_title_short is not null

Answer 3

update t1 set t1.race_title_short = (select distinct race_title_short from test t2 where t2.race_identifier_code = t1.race_identifier_code and t2.race_title_short is not null) from test t1