MySQL 合并多条件记录 GROUP_CONCAT

MYSQL 单表一对多查询，将多条记录合并成一条记录

语法结构：

GROUP_CONCAT(
  [ DISTINCT ] expr [,
  expr...] [
  ORDER BY { unsigned_integer | col_name | formula } [ ASC | DESC ] [,
  col...] ] [ SEPARATOR str_val ]
)

示例：

SELECT
  a.books,
  GROUP_CONCAT(a.name SEPARATOR '||') AS NAMES,
  GROUP_CONCAT(a.code SEPARATOR '||') AS codes
FROM
  temp_info a
GROUP BY a.books ;