關于empty set
mysql> SELECT goods_price FROM tdb_goods WHERE goods_cate='超極本';
Empty set (0.00 sec)
mysql> SELECT goods_price FROM tdb_goods WHERE goods_cate='筆記本';
+-------------+
| goods_price |
+-------------+
|??? 3399.000 |
|??? 4899.000 |
|??? 2799.000 |
+-------------+
3 rows in set (0.00 sec)????????
為什么查詢goods_cate=‘超極本’會出現Empty set (0.00 sec) 這種情況？
2018-02-04
因為你的漢子是錯的， 應該是select ?goods_price ?from goods where goods_cate ='超級本';
2018-03-23
我也碰到同樣問題了，笑死我啦。哈哈哈哈。謝謝你啦~~