关于empty set
mysql> SELECT goods_price FROM tdb_goods WHERE goods_cate='超极本';
Empty set (0.00 sec)
mysql> SELECT goods_price FROM tdb_goods WHERE goods_cate='笔记本';
+-------------+
| goods_price |
+-------------+
| 3399.000 |
| 4899.000 |
| 2799.000 |
+-------------+
3 rows in set (0.00 sec)
为什么查询goods_cate=‘超极本’会出现Empty set (0.00 sec) 这种情况？
