如果您不想查看表格中的所有列,只需指定感兴趣的列,以逗号分隔。例如,如果您想知道您的动物出生的时间,请选择姓名和出生栏:
mysql>SELECT name, birth FROM pet;
+----------+------------+
| name | birth |
+----------+------------+
| Fluffy | 1993-02-04 |
| Claws | 1994-03-17 |
| Buffy | 1989-05-13 |
| Fang | 1990-08-27 |
| Bowser | 1989-08-31 |
| Chirpy | 1998-09-11 |
| Whistler | 1997-12-09 |
| Slim | 1996-04-29 |
| Puffball | 1999-03-30 |
+----------+------------+
要了解谁拥有宠物,请使用以下查询:
mysql>SELECT owner FROM pet;
+--------+
| owner |
+--------+
| Harold |
| Gwen |
| Harold |
| Benny |
| Diane |
| Gwen |
| Gwen |
| Benny |
| Diane |
+--------+
请注意,查询只是从每个记录中检索所有者列,其中一些显示不止一次。要最小化输出,请通过添加关键字DISTINCT检索每个唯一输出记录一次:
mysql>SELECT DISTINCT owner FROM pet;
+--------+
| owner |
+--------+
| Benny |
| Diane |
| Gwen |
| Harold |
+--------+
您可以使用WHERE语句将行选择与列选择组合。例如,要仅为狗和猫生成出生日期,请使用以下查询:
mysql>SELECT name, species, birth FROM pet
->WHERE species = 'dog' OR species = 'cat';
+--------+---------+------------+
| name | species | birth |
+--------+---------+------------+
| Fluffy | cat | 1993-02-04 |
| Claws | cat | 1994-03-17 |
| Buffy | dog | 1989-05-13 |
| Fang | dog | 1990-08-27 |
| Bowser | dog | 1989-08-31 |
+--------+---------+------------+