select 指定列名，列名，列名 from 从表中
mysql> select id,price,name from products;
+------+-------+--------------------+
| id | price | name |
+------+-------+--------------------+
| 1 | 3.49 | Bird bean bag toy |
| 2 | 3.49 | qunkanlu |
| 3 | 4.9 | qunkanlu 50 number |
| 1 | 5.9 | hongqi |
+------+-------+--------------------+
4 rows in set (0.00 sec)
