如果我將NULL提供給MySQL的ASCII()函數，它會回傳什麼？

在這種情況下，ASCII()函數的輸出取決於我們是否將NULL作為字串提供，還是只提供NULL。以下範例將示範區別−

mysql> SELECT ASCII(null);
+-------------+
| ASCII(null) |
+-------------+
| NULL        |
+-------------+
1 row in set (0.00 sec)

mysql> SELECT ASCII('null');
+---------------+
| ASCII('null') |
+---------------+
| 110           |
+---------------+
1 row in set (0.00 sec)

mysql> Select ASCII(NULL);
+-------------+
| ASCII(NULL) |
+-------------+
| NULL        |
+-------------+
1 row in set (0.00 sec)

mysql> Select ASCII('NULL');
+---------------+
| ASCII('NULL') |
+---------------+
| 78            |
+---------------+
1 row in set (0.00 sec)

As we can observe from the above result set that when we will provide NULL or null as a string, ASCII() function will return the number code of the first character i.e. number code of the first character i.e. number code of of N in case of 'NULL' and number code of n in case of 'null', otherwise when we provide simply NULL then it returns NULL as output.

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