标签：SQ asc 扩展运算 通配符 bio _id and 工资 mys
星号 * 可以用在 select 子句中表示所有的属性。
mysql> select instructor.*
-> from instructor, teaches
-> where instructor.ID = teaches.ID;
+-------+------------+------------+----------+
| ID | name | dept_name | salary |
+-------+------------+------------+----------+
| 10101 | Srinivasan | Comp. Sci. | 65000.00 |
| 10101 | Srinivasan | Comp. Sci. | 65000.00 |
| 10101 | Srinivasan | Comp. Sci. | 65000.00 |
| 12121 | Wu | Finance | 90000.00 |
| 15151 | Mozart | Music | 40000.00 |
| 22222 | Einstein | Physics | 95000.00 |
| 32343 | El Said | History | 60000.00 |
| 45565 | Katz | Comp. Sci. | 75000.00 |
| 45565 | Katz | Comp. Sci. | 75000.00 |
| 76766 | Crick | Biology | 72000.00 |
| 76766 | Crick | Biology | 72000.00 |
| 83821 | Brandt | Comp. Sci. | 92000.00 |
| 83821 | Brandt | Comp. Sci. | 92000.00 |
| 83821 | Brandt | Comp. Sci. | 92000.00 |
| 98345 | Kim | Elec. Eng. | 80000.00 |
+-------+------------+------------+----------+
15 rows in set (0.01 sec)它返回了 instructor 中所有的属性。
SQL 为用户提供了一些结果显示的顺序的控制，order by 子句可以让查询结果中元组按升序显示，考虑按字典序列出 Physics 系的所有教师。
mysql> select name
-> from instructor
-> where dept_name = ‘Physics‘
-> order by name;
+----------+
| name |
+----------+
| Einstein |
| Gold |
+----------+
2 rows in set (0.00 sec)为了使用降序，我们可以用 desc 表示降序，完整地说，可以用 asc 表示升序，此外，排序可以在多个属性上进行，例如我们希望按 salary 的降序列出整个 instructor 关系，如果有几名教师工资相同，则按姓名升序排列。
mysql> select *
-> from instructor
-> order by salary desc, name asc;
+-------+------------+------------+----------+
| ID | name | dept_name | salary |
+-------+------------+------------+----------+
| 22222 | Einstein | Physics | 95000.00 |
| 83821 | Brandt | Comp. Sci. | 92000.00 |
| 12121 | Wu | Finance | 90000.00 |
| 33456 | Gold | Physics | 87000.00 |
| 98345 | Kim | Elec. Eng. | 80000.00 |
| 76543 | Singh | Finance | 80000.00 |
| 45565 | Katz | Comp. Sci. | 75000.00 |
| 76766 | Crick | Biology | 72000.00 |
| 10101 | Srinivasan | Comp. Sci. | 65000.00 |
| 58583 | Califieri | History | 62000.00 |
| 32343 | El Said | History | 60000.00 |
| 15151 | Mozart | Music | 40000.00 |
+-------+------------+------------+----------+
12 rows in set (0.00 sec)为了简化 where 子句，SQL 提供 between 运算符来说明一个值落在一个闭区间内。
考虑查询，找出工资在 90000 美元和 100000 美元之间的教师的姓名，直观地有
mysql> select name
-> from instructor
-> where salary <= 100000 and salary >= 90000;
+----------+
| name |
+----------+
| Wu |
| Einstein |
| Brandt |
+----------+
3 rows in set (0.01 sec)可以用 between 运算符改写为
mysql> select name
-> from instructor
-> where salary between 90000 and 100000;
+----------+
| name |
+----------+
| Wu |
| Einstein |
| Brandt |
+----------+
3 rows in set (0.01 sec)类似的有 not between 运算符
mysql> select name
-> from instructor
-> where salary not between 90000 and 100000;
+------------+
| name |
+------------+
| Srinivasan |
| Mozart |
| El Said |
| Gold |
| Katz |
| Califieri |
| Singh |
| Crick |
| Kim |
+------------+
9 rows in set (0.00 sec)where 子句还支持在元组上进行比较，考虑查询，查找 Biology 系讲授了课程的所有教师的姓名和他们所讲授的课程
mysql> select name, course_id
-> from instructor, teaches
-> where (instructor.ID, dept_name) = (teaches.ID, ‘Biology‘);
+-------+-----------+
| name | course_id |
+-------+-----------+
| Crick | BIO-101 |
| Crick | BIO-301 |
+-------+-----------+
2 rows in set (0.00 sec)标签：SQ asc 扩展运算 通配符 bio _id and 工资 mys
原文地址：https://www.cnblogs.com/wander4096/p/8831232.html
