sql - 如何更新仅显示一次的列中的值？

Question

如何仅更新仅在项目列中出现一次的那些项目的ID值？

表格1

id | item | price
-------------
10 | pen  | 10  
20 | pen  | 10   
30 | pen  | 10
30 | copy | 10
10 | book | 10
10 | ball | 10

Answer 1

update table set 
id = <whatever>
where
item in (select item from table group by item having count(*)=1)