Mysql GROUP_CONCAT 将数组某个字段连接起来

SELECT rec_id,GROUP_CONCAT(user_id)
FROM t1
GROUP BY rec_id

error: using group_concat in PHPMYADMIN will show the result as [BLOB – 3B]

can use:

SELECT rec_id,GROUP_CONCAT(CONVERT(user_id, CHAR(8)))
FROM t1
GROUP BY rec_id