MySQLやってて で知ったこと

now() に数値をプラスすると、数値になる。

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1. -- 普通  
2. mysql> select now();  
3. +---------------------+  
4. | now()               |  
5. +---------------------+  
6. | 2009-05-19 18:06:04 |  
7. +---------------------+  
8. 1 row in set (0.00 sec)  
9.   
10. -- 数値で  
11. mysql> select now() + 0;  
12. +-----------------------+  
13. | now() + 0             |  
14. +-----------------------+  
15. | 20090519180657.000000 |  
16. +-----------------------+  
17. 1 row in set (0.00 sec)  
18.   
19. -- 明日  
20. mysql> select now() + 1000000;  
21. +-----------------------+  
22. | now() + 1000000       |  
23. +-----------------------+  
24. | 20090520180610.000000 |  
25. +-----------------------+  
26. 1 row in set (0.00 sec)  

-- 普通
mysql> select now();
+---------------------+
| now()               |
+---------------------+
| 2009-05-19 18:06:04 |
+---------------------+
1 row in set (0.00 sec)

-- 数値で
mysql> select now() + 0;
+-----------------------+
| now() + 0             |
+-----------------------+
| 20090519180657.000000 |
+-----------------------+
1 row in set (0.00 sec)

-- 明日
mysql> select now() + 1000000;
+-----------------------+
| now() + 1000000       |
+-----------------------+
| 20090520180610.000000 |
+-----------------------+
1 row in set (0.00 sec)

っていうか、色々数値を突っ込んでみると数値になる？

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1. mysql> SELECT 0x61;  
2. +------+  
3. | 0x61 |  
4. +------+  
5. | a    |  
6. +------+  
7. 1 row in set (0.00 sec)  
8.   
9. mysql> SELECT 0x61 + 1;  
10. +----------+  
11. | 0x61 + 1 |  
12. +----------+  
13. |       98 |  
14. +----------+  
15. 1 row in set (0.00 sec)  

mysql> SELECT 0x61;
+------+
| 0x61 |
+------+
| a    |
+------+
1 row in set (0.00 sec)

mysql> SELECT 0x61 + 1;
+----------+
| 0x61 + 1 |
+----------+
|       98 |
+----------+
1 row in set (0.00 sec)