Question

I need to convert this PHP code into the MySQL query equivalent

$name = 'John Doe';
if($citizenship == 'o') {
  if($country == 'US') {
    $status = 'US-INTL';
  }else{
    $status = 'INTL';
  }
} elseif {
  $status = 'US'
}    

I am having trouble with MySQL’s if-then statements, even after reading their very minimal documentation on it. I’ve tried different nesting techniques but they all fail because I don’t know the syntax. For example:

SELECT name, IF citizenship='US' THEN 
  IF country='US' THEN 'US-INTL' AS status
  ELSEIF 'INTL' AS status
ELSE 
  'US' AS status
END IF
FROM people

MySQL should return something like

_________________
name     | status
-----------------
John Doe | US-INTL
-----------------

Answer 1

SELECT name,
       CASE WHEN citizenship = 'US'
            THEN CASE WHEN country='US'
                      THEN 'US-INTL'
                      ELSE 'INTL'
                 END
            ELSE 'US'
       END status

or mysql-specific way:

SELECT name,
       IF(citizenship = 'US',
          IF(country='US', 'US-INTL', 'INTL'),
          'US') status