如果您不想看到表格中的整行,只需命名您感兴趣的列,并用逗号分隔。例如,如果您想知道动物的出生时间,请选择name
和
birth
列:
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 |
+----------+------------+
要找出谁拥有宠物,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
owner
从每条记录中检索列,其中一些出现不止一次。为了最小化输出,通过添加关键字检索每个唯一的输出记录一次
DISTINCT
:
mysql> SELECT DISTINCT owner FROM pet;
+--------+
| owner |
+--------+
| Benny |
| Diane |
| Gwen |
| Harold |
+--------+
您可以使用WHERE
子句将行选择与列选择结合起来。例如,要仅获取狗和猫的出生日期,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 |
+--------+---------+------------+