select * from goods;
+------+------+
| id| price|
+------+------+
|1 | 10|
|1 | 20|
|1 | 20|
|2 | 20|
|3 | 200 |
|3 | 500 |
+------+------+
6 rows in set (0.00 sec)

以id分组，把price字段的值在同一行打印出来，逗号分隔(默认）

select id, group_concat(price) from goods group by id;
+------+--------------------+
| id| group_concat(price) |
+------+--------------------+
|1 | 10,20,20|
|2 | 20 |
|3 | 200,500|
+------+--------------------+
3 rows in set (0.00 sec)

以id分组，把price字段去重打印在一行，逗号分隔

select id,group_concat(distinct price) from goods group by id;
+------+-----------------------------+
| id| group_concat(distinct price) |
+------+-----------------------------+
|1 | 10,20|
|2 | 20 |
|3 | 200,500 |
+------+-----------------------------+
3 rows in set (0.00 sec)

以id分组，把price字段的值打印在一行，逗号分隔，按照price倒序排列

select id,group_concat(price order by price desc) from goods group by id;
+------+---------------------------------------+
| id| group_concat(price order by price desc) |
+------+---------------------------------------+
|1 | 20,20,10 |
|2 | 20|
|3 | 500,200|
+------+---------------------------------------+
3 rows in set (0.00 sec)

insert into select from 将查询到的记录插入到某个表中，

INSERT INTO db1_name(field1,field2) SELECT field1,field2 FROM db2_name

要求目标db2必须存在，下面测试一下，有两个表，结构如下

select * from insert_one;
+----+--------+-----+-----+
| id | name | age | sex |
+----+--------+-----+-----+
| 1 | 田小斯 | 25 | |
| 2 | 刘大牛 | 26 | |
| 3 | 郑大锤 | 28 | |
| 4 | 胡二狗 | 30 | |
+----+--------+-----+-----+
4 rows in set

 
select * from insert_sex;
+----+-----+
| id | sex |
+----+-----+
| 1 | 1 |
| 2 | 2 |
| 3 | 1 |
| 4 | 2 |
+----+-----+
4 rows in set

从表2中查找性别数据，插入到表1中

into insert_one(sex) select sex from insert_sex;
Query OK, 4 rows affected
select * from insert_one;
+----+--------+-----+-----+
| id | name | age | sex |
+----+--------+-----+-----+
| 1 | 田小斯 | 25 | |
| 2 | 刘大牛 | 26 | |
| 3 | 郑大锤 | 28 | |
| 4 | 胡二狗 | 30 | |
| 5 | | | 1 |
| 6 | | | 2 |
| 7 | | | 1 |
| 8 | | | 2 |
+----+--------+-----+-----+
8 rows in set

结果很尴尬，我是想要更新这张表的sex字段，而不是插入新的数据，那么这个命令只适用于要把数据导入空表中，所以在上面的实际需要中，我建立了新表mid，利用update来中转并更新数据
代码如下:UPDATE tb1,tb2 SET tb1.address=tb2.address WHERE tb1.name=tb2.name
根据条件匹配，把表1的数据替换为（更新为）表2的数据，表1和表2必须有关联才可以

update insert_one,insert_sex set insert_one.sex = insert_sex.sex where insert_one.id = insert_sex.id;
Query OK, 4 rows affected
select * from insert_one;
+----+--------+-----+-----+
| id | name | age | sex |
+----+--------+-----+-----+
| 1 | 田小斯 | 25 | 1 |
| 2 | 刘大牛 | 26 | 2 |
| 3 | 郑大锤 | 28 | 1 |
| 4 | 胡二狗 | 30 | 2 |
| 5 | | | 1 |
| 6 | | | 2 |
| 7 | | | 1 |
| 8 | | | 2 |
+----+--------+-----+-----+
8 rows in set

成功将数据更新到insert_one表的sex字段中。

更多关于MySQL相关内容感兴趣的读者可查看本站专题：《MySQL常用函数大汇总》、《MySQL日志操作技巧大全》、《MySQL事务操作技巧汇总》、《MySQL存储过程技巧大全》及《MySQL数据库锁相关技巧汇总》

希望本文所述对大家MySQL数据库计有所帮助。

您可能感兴趣的文章: