如何在mysql select语句中实现if else条件

Question

I want to check the value present in two fields of the table and based on that i want to display either field 1 or field 2. For Example:

Select name from users if address1='Mars' 
else select age from users if address2='Mars';

I want to achieve this using plane sql because I need to implement this in the controller of rails using ActiveRecord::Base.connection.select_values("sql query")

What should be the SQL query to achieve the same. I could not find it anywhere. Thanks in advance.

Answer 1

use CASE

SELECT  CASE 
            WHEN address1='Mars' THEN name 
            WHEN address2='Mars' THEN age
        END
FROM    users

Answer 2

请尝试User.find_by_sql("your sql query")