# 把1，2，3当作某个字段查询作为临时表
SELECT
	'1' AS val UNION ALL
SELECT
	'2' UNION ALL
SELECT
	'3'

# 临时表关联
SELECT
	temp_values.val
CASE
		WHEN a.value IS NOT NULL THEN
		'有' ELSE '没有' 
	END AS 是否存在 
FROM
	(SELECT '1' AS val UNION ALL SELECT '2' UNION ALL SELECT '3') AS temp_values
	LEFT JOIN a ON a.value = temp_values.val