语法: GROUP_CONCAT([DISTINCT] expr [,expr …] [ORDER BY {unsigned_integer | col_name | expr} [ASC | DESC] [,col_name …]] [SEPARATOR str_val])
说明:
- DISTINCT:去除重复值
- expr [,expr …]:一个或多个字段(或表达式)
- ORDER BY {unsigned_integer | col_name | expr} [ASC | DESC] [,col_name …]:根据字段或表达式进行排序,可多个
- SEPARATOR str_val:分隔符(默认为英文逗号)
实例
# test表
# id user_id
# 1 2
# 2 2
# 3 4
# 4 6
# 5 4
select GROUP_CONCAT(DISTINCT user_id) from test;
# 2,4,6