3.4.3 select子句中的属性说明
选中from子句结果关系中一个关系的所有属性
星号”*“可以用在select子句中表示”所有的属性”,因而,如下查询的select子句中使用instructor.*：
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| select instructor.*
from instructor,teaches
where instructor.ID=teaches.ID;
|
表示instructor中的所有属性都被选中。
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| mysql> select instructor.*
from instructor,teaches
where instructor.ID=teaches.ID;
+-------+------------+------------+--------+
| ID | name | dept_name | salary |
+-------+------------+------------+--------+
| 76766 | Crick | Biology | 72000 |
| 76766 | Crick | Biology | 72000 |
| 10101 | Srinivasan | Comp. Sci. | 65000 |
| 45565 | Katz | Comp. Sci. | 75000 |
| 83821 | Brandt | Comp. Sci. | 92000 |
| 83821 | Brandt | Comp. Sci. | 92000 |
| 10101 | Srinivasan | Comp. Sci. | 65000 |
| 45565 | Katz | Comp. Sci. | 75000 |
| 83821 | Brandt | Comp. Sci. | 92000 |
| 10101 | Srinivasan | Comp. Sci. | 65000 |
| 98345 | Kim | Elec. Eng. | 80000 |
| 12121 | Wu | Finance | 90000 |
| 32343 | El Said | History | 60000 |
| 15151 | Mozart | Music | 40000 |
| 22222 | Einstein | Physics | 95000 |
+-------+------------+------------+--------+
15 rows in set
|
选中from子句结果关系的所有属性
形如select * from ...的select子句表示from子句结果关系的所有属性都被选中,例如:
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| select *
from instructor,teaches
where instructor.ID=teaches.ID;
|
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| mysql> select *
from instructor,teaches
where instructor.ID=teaches.ID;
+-------+------------+------------+--------+-------+-----------+--------+----------+------+
| ID | name | dept_name | salary | ID | course_id | sec_id | semester | year |
+-------+------------+------------+--------+-------+-----------+--------+----------+------+
| 76766 | Crick | Biology | 72000 | 76766 | BIO-101 | 1 | Summer | 2009 |
| 76766 | Crick | Biology | 72000 | 76766 | BIO-301 | 1 | Summer | 2010 |
| 10101 | Srinivasan | Comp. Sci. | 65000 | 10101 | CS-101 | 1 | Fall | 2009 |
| 45565 | Katz | Comp. Sci. | 75000 | 45565 | CS-101 | 1 | Spring | 2010 |
| 83821 | Brandt | Comp. Sci. | 92000 | 83821 | CS-190 | 1 | Spring | 2009 |
| 83821 | Brandt | Comp. Sci. | 92000 | 83821 | CS-190 | 2 | Spring | 2009 |
| 10101 | Srinivasan | Comp. Sci. | 65000 | 10101 | CS-315 | 1 | Spring | 2010 |
| 45565 | Katz | Comp. Sci. | 75000 | 45565 | CS-319 | 1 | Spring | 2010 |
| 83821 | Brandt | Comp. Sci. | 92000 | 83821 | CS-319 | 2 | Spring | 2010 |
| 10101 | Srinivasan | Comp. Sci. | 65000 | 10101 | CS-347 | 1 | Fall | 2009 |
| 98345 | Kim | Elec. Eng. | 80000 | 98345 | EE-181 | 1 | Spring | 2009 |
| 12121 | Wu | Finance | 90000 | 12121 | FIN-201 | 1 | Spring | 2010 |
| 32343 | El Said | History | 60000 | 32343 | HIS-351 | 1 | Spring | 2010 |
| 15151 | Mozart | Music | 40000 | 15151 | MU-199 | 1 | Spring | 2010 |
| 22222 | Einstein | Physics | 95000 | 22222 | PHY-101 | 1 | Fall | 2009 |
+-------+------------+------------+--------+-------+-----------+--------+----------+------+
15 rows in set
|