mysql - MySQL：创建逗号分隔列表并在 IN 中使用

Question

我的功能代码如下。

DECLARE ids VARCHAR(55);
SELECT  GROUP_CONCAT(id) INTO ids 
        FROM tableName WHERE ...;
SELECT CONCAT(GROUP_CONCAT(id), ids ) INTO ids FROM tableName .....;
SELECT column_name FROM tableName WHERE id IN (**ids**);

在此我使用两个 select 语句创建 id 列表并应用到 IN 列表中。它给了我空结果。如果我 CAST 像 CONCAT(GROUP_CONCAT(id), CAST(ids as char) ) 这样的 ID，那么它会给我第一行结果。

Answer 1

试试这个：

DECLARE ids VARCHAR(55);
SELECT GROUP_CONCAT(id) INTO ids 
FROM (SELECT id 
      FROM tableName 
      WHERE...
      UNION 
      SELECT id 
      FROM tableName
      WHERE....
) AS A;

SELECT column_name FROM tableName WHERE FIND_IN_SET(id, ids);

Answer 2

我已经通过以下代码解决了这个问题

DECLARE ids VARCHAR(55);
SELECT GROUP_CONCAT(id SEPARATOR ',') INTO ids  FROM tableName WHERE ...;
SELECT CONCAT_WS(',', CAST(GROUP_CONCAT(id SEPARATOR ',')AS CHAR), CAST(ids AS CHAR)) INTO ids FROM tableName .....;
SELECT column_name FROM tableName WHERE FIND_IN_SET (id, ids );