sql - 是否可以在 sql 的表中看到“null”而不是空白

Question

+----+----------+-----+-----------+----------+
| ID | NAME     | AGE | ADDRESS   | SALARY   |
+----+----------+-----+-----------+----------+
|  1 | Ramesh   |  32 | Ahmedabad |  2000.00 |
|  2 | Khilan   |  25 | Delhi     |  1500.00 |
|  3 | kaushik  |  23 | Kota      |  2000.00 |
|  4 | Chaitali |  25 | Mumbai    |  6500.00 |
|  5 | Hardik   |  27 | Bhopal    |  8500.00 |
|  6 | Komal    |  22 | MP        |          |
|  7 | Muffy    |  24 | Indore    |          |
+----+----------+-----+-----------+----------+

如何在插入值时在 id 6,7 中为薪金列打印上表中的空值而不是空格。

 +----+----------+-----+-----------+----------+
| ID | NAME     | AGE | ADDRESS   | SALARY   |
+----+----------+-----+-----------+----------+
|  1 | Ramesh   |  32 | Ahmedabad |  2000.00 |
|  2 | Khilan   |  25 | Delhi     |  1500.00 |
|  3 | kaushik  |  23 | Kota      |  2000.00 |
|  4 | Chaitali |  25 | Mumbai    |  6500.00 |
|  5 | Hardik   |  27 | Bhopal    |  8500.00 |
|  6 | Komal    |  22 | MP        |   null   |
|  7 | Muffy    |  24 | Indore    |   null   |
+----+----------+-----+-----------+----------+

Answer 1

根据 RDBMS，您可以在 SELECT 中使用 ISNULL() 或 IFNULL()。您的查询将如下所示：

SELECT ID, NAME, AGE, ADDRESS, IFNULL(SALARY, "null") FROM YOURTABLE

Answer 2

Oracle相当于neelsg的答案，

SELECT id, name, age, address, NVL(salary, "null") FROM yourtable