MySQL为选择添加新列

Question

我拥有以下表格:

+-----+------------------+-------------+
| id  | datenum          | F1_baro_20_ |
+-----+------------------+-------------+
|   1 | 734152.000000000 |     1005.21 |
|   2 | 734152.006944445 |     1005.26 |
+-----+------------------+-------------+

当我进行选择时，我想要添加一列。

例如：

SELECT id,datenum, F1_baro_20_ FROM test

我想要添加一列，类似于这样：

SELECT id,datenum, F1_baro_20_, new_column=1 FROM test

+-----+------------------+-------------+------------+
| id  | datenum          | F1_baro_20_ |new_column  |
+-----+------------------+-------------+------------+
|   1 | 734152.000000000 |     1005.21 |       1    |
|   2 | 734152.006944445 |     1005.26 |       1    |
+-----+------------------+-------------+------------+

- Mokus

Answer 1

SELECT id, datenum, F1_baro_20_, 1 AS new_column FROM test;

这甚至适用于更复杂的表达式，例如：

SELECT id, datenum, F1_baro_20_, (IF id = 2 THEN 1 ELSE 0) AS id_is_two FROM test;

- Emil Vikström

---

是的，我也尝试过带括号的这个 SELECT id, datenum, F1_baro_20_, (1 AS new_column) FROM test;，那就是问题所在。谢谢。 - Mokus