义齿

再問合せ
select distinctフィールドfromデータベース
 
(1)クエリーtb_students_infoテーブルのすべてのageの実行結果を以下に示す.

mysql> SELECT age FROM tb_students_info;
+------+
| age  |
+------+
|   25 |
|   23 |
|   23 |
|   22 |
|   24 |
|   21 |
|   22 |
|   23 |
|   22 |
|   23 |
+------+
10 rows in set (0.00 sec)


（2）   tb_students_info    age     ，   age          ，

mysql> SELECT  DISTINCT age
    -> FROM tb_students_info;
+------+
| age  |
+------+
|   25 |
|   23 |
|   22 |
|   24 |
|   21 |
+------+
5 rows in set (0.11 sec)