【MySQL】每日一题2020-02-25
2020-02-25 本文已影响0人
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create table t_0225 (hobby varchar(50))ENGINE=INNODB DEFAULT CHARSET=utf8;
insert into t_0225 values('篮球');
insert into t_0225 values('足球');
insert into t_0225 values ('羽毛球');
insert into t_0225 values('乒乓球');
mysql> select group_concat(hobby) as hobby from t_0225;
+-----------------------------------+
| hobby |
+-----------------------------------+
| 篮球,足球,羽毛球,乒乓球 |
+-----------------------------------+
1 row in set (0.00 sec)
mysql> select substring_index(substring_index(hobby,',',help_topic_id+1),',',-1) as hobby from t_0225 left join mysql.help_topic on (length(hobby)-length(replace(hobby,',',''))+1)>help_topic_id;
+-----------+
| hobby |
+-----------+
| 篮球 |
| 足球 |
| 羽毛球 |
| 乒乓球 |
+-----------+
4 rows in set (0.00 sec)
