其他

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 tb31;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  12 | kakaka |    1 |
|  13 | papapa |    2 |
|  14 | fafafa |    1 |
|  15 | kakaka |    1 |
|  16 | opop   |    2 |
|  17 | opop   |    2 |
+-----+--------+------+
6 rows in set (0.00 sec)

MariaDB [test]> select * from tb31 limit 2;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  12 | kakaka |    1 |
|  13 | papapa |    2 |
+-----+--------+------+
2 rows in set (0.00 sec)

MariaDB [test]> select * from tb31 limit 3;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  12 | kakaka |    1 |
|  13 | papapa |    2 |
|  14 | fafafa |    1 |
+-----+--------+------+
3 rows in set (0.00 sec)

MariaDB [test]> select * from tb31 limit 4;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  12 | kakaka |    1 |
|  13 | papapa |    2 |
|  14 | fafafa |    1 |
|  15 | kakaka |    1 |
+-----+--------+------+
4 rows in set (0.00 sec)

MariaDB [test]> select * from tb31;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  12 | kakaka |    1 |
|  13 | papapa |    2 |
|  14 | fafafa |    1 |
|  15 | kakaka |    1 |
|  16 | opop   |    2 |
|  17 | opop   |    2 |
+-----+--------+------+
6 rows in set (0.00 sec)

MariaDB [test]> select * from tb31 limit 2,1;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  14 | fafafa |    1 |
+-----+--------+------+
1 row in set (0.00 sec)

MariaDB [test]> select * from tb31 limit 1,1;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  13 | papapa |    2 |
+-----+--------+------+
1 row in set (0.00 sec)

MariaDB [test]> select * from tb31 limit 1,3;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  13 | papapa |    2 |
|  14 | fafafa |    1 |
|  15 | kakaka |    1 |
+-----+--------+------+
3 rows in set (0.00 sec)

MariaDB [test]> select * from tb31 limit 1,2;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  13 | papapa |    2 |
|  14 | fafafa |    1 |
+-----+--------+------+
2 rows in set (0.00 sec)

MariaDB [test]> select * from tb31 limit 1,1;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  13 | papapa |    2 |
+-----+--------+------+
1 row in set (0.00 sec)

MariaDB [test]> select * from tb31 limit 1,2;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  13 | papapa |    2 |
|  14 | fafafa |    1 |
+-----+--------+------+
2 rows in set (0.00 sec)

MariaDB [test]> select * from tb31 limit 1,3;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  13 | papapa |    2 |
|  14 | fafafa |    1 |
|  15 | kakaka |    1 |
+-----+--------+------+
3 rows in set (0.00 sec)

MariaDB [test]> select * from tb31 limit 1,4;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  13 | papapa |    2 |
|  14 | fafafa |    1 |
|  15 | kakaka |    1 |
|  16 | opop   |    2 |
+-----+--------+------+
4 rows in set (0.00 sec)

MariaDB [test]> select * from tb31 limit 0,2;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  12 | kakaka |    1 |
|  13 | papapa |    2 |
+-----+--------+------+
2 rows in set (0.00 sec)

MariaDB [test]> select * from tb31 limit 2,2;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  14 | fafafa |    1 |
|  15 | kakaka |    1 |
+-----+--------+------+
2 rows in set (0.00 sec)

MariaDB [test]> select * from tb31;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  12 | kakaka |    1 |
|  13 | papapa |    2 |
|  14 | fafafa |    1 |
|  15 | kakaka |    1 |
|  16 | opop   |    2 |
|  17 | opop   |    2 |
+-----+--------+------+
6 rows in set (0.00 sec)

MariaDB [test]> select * from tb31 limit 0,2;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  12 | kakaka |    1 |
|  13 | papapa |    2 |
+-----+--------+------+
2 rows in set (0.00 sec)

MariaDB [test]> select * from tb31 limit 2,2;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  14 | fafafa |    1 |
|  15 | kakaka |    1 |
+-----+--------+------+
2 rows in set (0.00 sec)

MariaDB [test]> select * from tb31 limit 4,2;
+-----+------+------+
| nid | name | age  |
+-----+------+------+
|  16 | opop |    2 |
|  17 | opop |    2 |
+-----+------+------+
2 rows in set (0.00 sec)

MariaDB [test]> select * from tb31 limit 2 offset 0;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  12 | kakaka |    1 |
|  13 | papapa |    2 |
+-----+--------+------+
2 rows in set (0.00 sec)

MariaDB [test]> select * from tb31 limit 2 offset 2;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  14 | fafafa |    1 |
|  15 | kakaka |    1 |
+-----+--------+------+
2 rows in set (0.00 sec)

MariaDB [test]> select * from tb31 limit 2 offset 4;
+-----+------+------+
| nid | name | age  |
+-----+------+------+
|  16 | opop |    2 |
|  17 | opop |    2 |
+-----+------+------+
2 rows in set (0.01 sec)

MariaDB [test]> select * from tb31;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  12 | kakaka |    1 |
|  13 | papapa |    2 |
|  14 | fafafa |    1 |
|  15 | kakaka |    1 |
|  16 | opop   |    2 |
|  17 | opop   |    2 |
+-----+--------+------+
6 rows in set (0.00 sec)

MariaDB [test]> select * from tb31 order by nid asc;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  12 | kakaka |    1 |
|  13 | papapa |    2 |
|  14 | fafafa |    1 |
|  15 | kakaka |    1 |
|  16 | opop   |    2 |
|  17 | opop   |    2 |
+-----+--------+------+
6 rows in set (0.00 sec)

MariaDB [test]> select * from tb31 order by nid desc;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  17 | opop   |    2 |
|  16 | opop   |    2 |
|  15 | kakaka |    1 |
|  14 | fafafa |    1 |
|  13 | papapa |    2 |
|  12 | kakaka |    1 |
+-----+--------+------+
6 rows in set (0.00 sec)

MariaDB [test]> select * from tb31;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  12 | kakaka |    1 |
|  13 | papapa |    2 |
|  14 | fafafa |    1 |
|  15 | kakaka |    1 |
|  16 | opop   |    2 |
|  17 | opop   |    2 |
+-----+--------+------+
6 rows in set (0.00 sec)

MariaDB [test]> select * from tb31 order by name desc;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  13 | papapa |    2 |
|  16 | opop   |    2 |
|  17 | opop   |    2 |
|  12 | kakaka |    1 |
|  15 | kakaka |    1 |
|  14 | fafafa |    1 |
+-----+--------+------+
6 rows in set (0.00 sec)

MariaDB [test]> select * from tb31 order by name desc,nid desc;
+-----+--------+------+
| nid | name   | age  |
+-----+--------+------+
|  13 | papapa |    2 |
|  17 | opop   |    2 |
|  16 | opop   |    2 |
|  15 | kakaka |    1 |
|  12 | kakaka |    1 |
|  14 | fafafa |    1 |
+-----+--------+------+
6 rows in set (0.00 sec)