其它

a、条件
select * from 表 where id > 1 and name != 'alex' and num = 12;

select * from 表 where id between 5 and 16;

select * from 表 where id in (11,22,33)
select * from 表 where id not in (11,22,33)
select * from 表 where id in (select nid from 表)

b、通配符
select * from 表 where name like 'ale%' - ale开头的所有（多个字符串）
select * from 表 where name like 'ale_' - ale开头的所有（一个字符）

c、限制
select * from 表 limit 5; - 前5行
select * from 表 limit 4,5; - 从第4行开始的5行
select * from 表 limit 5 offset 4 - 从第4行开始的5行

d、排序
select * from 表 order by 列 asc - 根据 “列” 从小到大排列
select * from 表 order by 列 desc - 根据 “列” 从大到小排列
select * from 表 order by 列1 desc,列2 asc - 根据 “列1” 从大到小排列，如果相同则按列2从小到大排序

e、分组
select num from 表 group by num
select num,nid from 表 group by num,nid
select num,nid from 表 where nid > 10 group by num,nid order nid desc
select num,nid,count(*),sum(score),max(score),min(score) from 表 group by num,nid

select num from 表 group by num having max(id) > 10

特别的：group by 必须在where之后，order by之前

f、连表
无对应关系则不显示
select A.num, A.name, B.name
from A,B
Where A.nid = B.nid

无对应关系则不显示
select A.num, A.name, B.name
from A inner join B
on A.nid = B.nid

A表所有显示，如果B中无对应关系，则值为null
select A.num, A.name, B.name
from A left join B
on A.nid = B.nid

B表所有显示，如果B中无对应关系，则值为null
select A.num, A.name, B.name
from A right join B
on A.nid = B.nid

g、组合
组合，自动处理重合
select nickname
from A
union
select name
from B

组合，不处理重合
select nickname
from A
union all
select name
from B

MariaDB [test]> select * from userinfo;
+-----+------+------+----------+
| nid | name | age  | part_nid |
+-----+------+------+----------+
|   1 | h    |   19 |        2 |
|   2 | hh   |   19 |        2 |
|   3 | hhh  |   19 |        2 |
+-----+------+------+----------+
3 rows in set (0.00 sec)

MariaDB [test]> select * from part;
+-----+---------+
| nid | caption |
+-----+---------+
|   1 | IT      |
|   2 | TI      |
|   3 | SA      |
|   4 | DEV     |
+-----+---------+
4 rows in set (0.00 sec)

MariaDB [test]> insert into userinfo(name,age,part_nid) values('b',11,1),('c',12,1),('d',18,4);
Query OK, 3 rows affected (0.01 sec)
Records: 3  Duplicates: 0  Warnings: 0

MariaDB [test]> select * from part;
+-----+---------+
| nid | caption |
+-----+---------+
|   1 | IT      |
|   2 | TI      |
|   3 | SA      |
|   4 | DEV     |
+-----+---------+
4 rows in set (0.00 sec)

MariaDB [test]> select * from userinfo;
+-----+------+------+----------+
| nid | name | age  | part_nid |
+-----+------+------+----------+
|   1 | h    |   19 |        2 |
|   2 | hh   |   19 |        2 |
|   3 | hhh  |   19 |        2 |
|   5 | b    |   11 |        1 |
|   6 | c    |   12 |        1 |
|   7 | d    |   18 |        4 |
+-----+------+------+----------+
6 rows in set (0.00 sec)

MariaDB [test]> select * from userinfo where part_nid=2;
+-----+------+------+----------+
| nid | name | age  | part_nid |
+-----+------+------+----------+
|   1 | h    |   19 |        2 |
|   2 | hh   |   19 |        2 |
|   3 | hhh  |   19 |        2 |
+-----+------+------+----------+
3 rows in set (0.00 sec)

MariaDB [test]> select * from userinfo where part_nid=1;
+-----+------+------+----------+
| nid | name | age  | part_nid |
+-----+------+------+----------+
|   5 | b    |   11 |        1 |
|   6 | c    |   12 |        1 |
+-----+------+------+----------+
2 rows in set (0.01 sec)

MariaDB [test]> select * from userinfo where part_nid=3;
Empty set (0.00 sec)

MariaDB [test]> select * from userinfo where part_nid=4;
+-----+------+------+----------+
| nid | name | age  | part_nid |
+-----+------+------+----------+
|   7 | d    |   18 |        4 |
+-----+------+------+----------+
1 row in set (0.00 sec)

MariaDB [test]> select * from userinfo;
+-----+------+------+----------+
| nid | name | age  | part_nid |
+-----+------+------+----------+
|   1 | h    |   19 |        2 |
|   2 | hh   |   19 |        2 |
|   3 | hhh  |   19 |        2 |
|   5 | b    |   11 |        1 |
|   6 | c    |   12 |        1 |
|   7 | d    |   18 |        4 |
+-----+------+------+----------+
6 rows in set (0.00 sec)

MariaDB [test]> select part_nid from userinfo group by part_nid;
+----------+
| part_nid |
+----------+
|        1 |
|        2 |
|        4 |
+----------+
3 rows in set (0.00 sec)

MariaDB [test]> select part_nid,nid from userinfo group by part_nid;
+----------+-----+
| part_nid | nid |
+----------+-----+
|        1 |   5 |
|        2 |   1 |
|        4 |   7 |
+----------+-----+
3 rows in set (0.00 sec)

MariaDB [test]> select part_nid,max(nid) from userinfo group by part_nid;
+----------+----------+
| part_nid | max(nid) |
+----------+----------+
|        1 |        6 |
|        2 |        3 |
|        4 |        7 |
+----------+----------+
3 rows in set (0.00 sec)

MariaDB [test]> select part_nid,max(nid),min(nid) from userinfo group by part_nid;
+----------+----------+----------+
| part_nid | max(nid) | min(nid) |
+----------+----------+----------+
|        1 |        6 |        5 |
|        2 |        3 |        1 |
|        4 |        7 |        7 |
+----------+----------+----------+
3 rows in set (0.00 sec)

MariaDB [test]> select part_nid,max(nid),min(nid),sum(nid) from userinfo group by part_nid;
+----------+----------+----------+----------+
| part_nid | max(nid) | min(nid) | sum(nid) |
+----------+----------+----------+----------+
|        1 |        6 |        5 |       11 |
|        2 |        3 |        1 |        6 |
|        4 |        7 |        7 |        7 |
+----------+----------+----------+----------+
3 rows in set (0.00 sec)

MariaDB [test]> select part_nid,max(nid),min(nid),sum(nid),count(nid) from userinfo group by part_nid;
+----------+----------+----------+----------+------------+
| part_nid | max(nid) | min(nid) | sum(nid) | count(nid) |
+----------+----------+----------+----------+------------+
|        1 |        6 |        5 |       11 |          2 |
|        2 |        3 |        1 |        6 |          3 |
|        4 |        7 |        7 |        7 |          1 |
+----------+----------+----------+----------+------------+
3 rows in set (0.00 sec)

MariaDB [test]> select part_nid,count(nid) from userinfo group by part_nid;
+----------+------------+
| part_nid | count(nid) |
+----------+------------+
|        1 |          2 |
|        2 |          3 |
|        4 |          1 |
+----------+------------+
3 rows in set (0.01 sec)

MariaDB [test]> select part_nid as a,count(nid) as b from userinfo group by part_nid;
+------+---+
| a    | b |
+------+---+
|    1 | 2 |
|    2 | 3 |
|    4 | 1 |
+------+---+
3 rows in set (0.00 sec)

MariaDB [test]> select part_nid,count(nid) from userinfo where count(nid)>1 group by part_nid;
ERROR 1111 (HY000): Invalid use of group function

MariaDB [test]> select part_nid,count(nid) from userinfo group by part_nid where count(nid)>1;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'where count(nid)>1' at line 1

MariaDB [test]> select part_nid,count(nid) from userinfo group by part_nid having count(nid)>1;
+----------+------------+
| part_nid | count(nid) |
+----------+------------+
|        1 |          2 |
|        2 |          3 |
+----------+------------+
2 rows in set (0.00 sec)