Modify column value based on some conditions

Question

Given the following table:

 ... |  item  | type | ...
 ... |    A   |  1   | ...
 ... |    B   |  2   | ...
 ... |    A   |  2   | ...
 ... |    A   |  3   | ...
 ... |    B   |  3   | ...
 ... |    A   |  2   | ...

Let's call items by pairings (A1, B2, A2, etc). There is an error in the table where an A3 should actually be C3.

I want to write a query that will return rows and change the item column to C if the row returned A3.

Example query that doesn't work:

SELECT (item like 'A' ? (type == 3? 'C' : 'A') : item) as "item", type from table; 

My desired output would be:

"item" | type
   A   |  1  
   B   |  2  
   A   |  2   
   C   |  3  
   B   |  3   
   A   |  2   

What is the correct way of doing this? If possible?

Answer 1

   update table tablename
     set item='C'
     where type=3 and item='A'

If you don't need updating these values in the table, but to get replaced values them as a result of the select, then

   select 
      case when item='A' and type=3 then 'C' 
           else item 
           end as newitem, type from tablename