sql - How to select the comparison of two columns as one column in Oracle

Question

I cannot figure out how to add a column to my SELECT query indicating whether two columns contain the same data in Oracle.

I would like to write a query like:

select column1, column2, column1=column2 from table

and, if I have this table:

+---------+---------+
| column1 | column2 |
+---------+---------+
| value1  | value1  |
| value2  | value3  |
| value4  | value4  |
+---------+---------+

get a result like:

+---------+---------+-----------------+
| column1 | column2 | column1=column2 |
+---------+---------+-----------------+
| value1  | value1  | true            |
| value2  | value3  | false           |
| value4  | value4  | true            |
+---------+---------+-----------------+

What is the correct syntax to do this?

Answer 1

If you want to consider null values equality too, try the following

select column1, column2, 
   case
      when column1 is NULL and column2 is NULL then 'true'  
      when column1=column2 then 'true' 
      else 'false' 
   end 
from table;