Question

所以我有一个像

这样的查询

SELECT * FROM table WHERE id IN (1,2,3) LIMIT 10

是否可以限制数组中每个元素的输出数量，如

SELECT * FROM table WHERE id 1 LIMIT 10
SELECT * FROM table WHERE id 2 LIMIT 10
SELECT * FROM table WHERE id 3 LIMIT 10

Answer 1

是的，您可以使用变量：

SELECT *
FROM (
  SELECT *,
         @seq := IF(id = @id, @seq + 1,
                    IF(@id := id, 1, 1)) AS seq 
  FROM table 
  CROSS JOIN (SELECT @seq := 0, @id := 0) AS vars
  WHERE id IN (1,2,3) 
  ORDER BY id) AS t
WHERE t.seq <= 10

Answer 2

如果你害怕MySQL变量（我是），你也可以使用UNION查询：

(SELECT * FROM table WHERE id = 1 LIMIT 10)
UNION ALL
(SELECT * FROM table WHERE id = 2 LIMIT 10)
UNION ALL
(SELECT * FROM table WHERE id = 3 LIMIT 10)

MySQL其中IN，限制输出

2 个答案: