Mysql 如何将If-Else-End-If添加到此查询

当找不到值时，以下查询返回NULL。我如何在这两个字段周围分别添加一个If，这样如果它为Null，那么就不会找到else返回查询结果

SET @id = 26;
SELECT 
(SELECT id  FROM devTable WHERE id <= @id AND country = 'US' ORDER BY id DESC LIMIT 9,1) AS `prev`,
(SELECT id  FROM devTable WHERE id >= @id AND country = 'US' ORDER BY id ASC  LIMIT 1,1) AS `next`

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查找T-sqlexists命令

比如：

使用：

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TSQL？此问题标记为mysql，而不是sql server

IF EXISTS( SELECT STUFF FROM JUNK WHERE ITEMS=5) THEN
BEGIN
SELECT "HAVE JUNK"  -- OR PRINT, SET, ...
END
ELSE
BEGIN
SELECT "SORRY, DON'T HAVE JUNK" -- OR PRINT, SET, ...
END
END

SET @id = 26;
SELECT 
IFNULL(
  (SELECT id FROM devTable WHERE id <= @id AND country = 'US' ORDER BY id DESC LIMIT 9,1),
  'Not Found') AS prev,
IFNULL(
  (SELECT id FROM devTable WHERE id >= @id AND country = 'US' ORDER BY id ASC  LIMIT 1,1),
  'Not Found') AS next