完整语法:
group_concat([DISTINCT] 要连接的字段 [Order BY ASC/DESC 排序字段] [Separator ‘分隔符’])
1 | SELECT * FROM `sqltest` |
如果按照group_id分组,会自动去重
1 | SELECT * FROM `sqltest` GROUP BY group_id |
想要类别按组分类集中到一起,就要用Group_concat
1 | SELECT group_id,GROUP_CONCAT(category) FROM `sqltest` GROUP BY group_id |
还有几种扩展:
①可以给类别去重
1 | SELECT group_id,GROUP_CONCAT( DISTINCT category) FROM `sqltest` GROUP BY group_id |
②给类别排序
1 | SELECT group_id,GROUP_CONCAT(category ORDER BY category DESC ) FROM `sqltest` GROUP BY group_id |
③给类别更改分隔符
1 | SELECT group_id,GROUP_CONCAT(category SEPARATOR '_' ) FROM `sqltest` GROUP BY group_id |
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