mysql - Union - 同一张表，不包括以前的结果 MySQL

Question

我正在尝试编写一个查询，它将：

• 运行查询，给我 (x) 行数（限制 4）
• 如果该查询没有给我所需的 4，请运行第二个查询限制 4-(x) 并从第一个查询中排除 id
• 第三个查询的行为类似于第二个

我有这个：

(SELECT *, 1 as SORY_QUERY1 FROM xbamZ where state = 'Minnesota' and industry = 'Miscellaneous' and id != '229' limit 4) 
UNION 
(SELECT *, 2 FROM xbamZ where state = 'Minnesota' limit 2) 
UNION 
(SELECT *, 3 FROM xbamZ where industry = 'Miscellaneous' limit 1)

我是如何（或者是？）这样做？我接近了吗？这个查询给了我重复

Answer 1

我认为没有必要 union 和三个selects。一个也可以

SELECT a.*
FROM
(
SELECT xbamZ.*,
CASE 
  WHEN state = 'Minnesota' and industry = 'Miscellaneous' and id != '229' THEN 1
  WHEN state = 'Minnesota' THEN 2
  WHEN industry = 'Miscellaneous' THEN 3
END as rnk
FROM xbamZ 
where state = 'Minnesota' or industry = 'Miscellaneous' 
)a 
ORDER BY rnk
LIMIT 4;