忽略輸入類型

Question

我有問題 。

mysql> SELECT 0 IN ('a',4);
+--------------+
| 0 IN ('a',4) |
+--------------+
|            1 |
+--------------+
1 row in set, 1 warning (0.00 sec)

mysql> SELECT 1 IN ('a',4);
+--------------+
| 1 IN ('a',4) |
+--------------+
|            0 |
+--------------+
1 row in set, 1 warning (0.00 sec)

'a'強制轉換為0。如何使'a'不強制轉換..？

Answer 1

將您要比較的值轉換為字符串：

mysql> SELECT '0' IN ('a', '4');
+-----------------+
| '0' IN ('a', 4) |
+-----------------+
|               0 |
+-----------------+

mysql> SELECT '4' IN ('a', '4');
+-----------------+
| '4' IN ('a', 4) |
+-----------------+
|               1 |
+-----------------+