CREATE TABLE `C` (
  `int_nokey` int(11) DEFAULT NULL,
  `int_key` int(11) DEFAULT NULL,
  `varchar_nokey` varchar(1) DEFAULT NULL,
  KEY `int_key` (`int_key`),
  KEY `varchar_key` (`int_key`)
)  DEFAULT CHARSET=latin1;
INSERT INTO `C` VALUES (9,3,'m');
CREATE TABLE `D` (
  `int_nokey` int(11) DEFAULT NULL,
  `int_key` int(11) DEFAULT NULL,
  `varchar_nokey` varchar(1) DEFAULT NULL,
  KEY `int_key` (`int_key`),
  KEY `varchar_key` (`int_key`)
)  DEFAULT CHARSET=latin1;
INSERT INTO `D` VALUES (1,5,'j'),(8,NULL,'f');

EXPLAIN EXTENDED SELECT table2 .`int_key` field12  , (  
SELECT  SUM( `int_nokey`  )  
FROM D  
WHERE `int_key`  = table1 .`int_key`  )  
FROM C table1  RIGHT  JOIN C table2  ON table1 .`varchar_nokey` ;
SHOW WARNINGS;

SELECT table2 .`int_key` field12  , (  
SELECT  SUM( `int_nokey`  )  
FROM D  
WHERE `int_key`  = table1 .`int_key`  )  
FROM C table1  RIGHT  JOIN C table2  ON table1 .`varchar_nokey` ;

EXPLAIN EXTENDED SELECT table2 .`int_key` field12  , (  
SELECT  SUM( `int_nokey`  )  
FROM D  
WHERE `int_key`  = table1 .`int_key`  )  
FROM C table1  RIGHT  JOIN C table2  ON table1 .`varchar_nokey` 
GROUP  BY field12  ;

SELECT table2 .`int_key` field12  , (  
SELECT  SUM( `int_nokey`  )  
FROM D  
WHERE `int_key`  = table1 .`int_key`  )  
FROM C table1  RIGHT  JOIN C table2  ON table1 .`varchar_nokey` 
GROUP  BY field12  ;

# Analysis of the expected result. First the right join:
# table1.varchar_nokey is 'm' which evaluates to false
# so right join outputs table2//table1 record like this:
# 9 3 m null null null
# thus table.int_key is null in the subquery, and so the WHERE
# is false (as D.int_key = NULL is a false condition)
# so the SUM is over an empty table so NULL per the manual;
# so we get as output 3,NULL;
# we have a single row so the GROUP BY should do nothing,
# so we get as final output 3,NULL.
# But 3,8 in mysql-next-bugfixing if there is GROUP BY.