mysql> select concat('aaa','bbb','ccc');
+---------------------------+
| concat('aaa','bbb','ccc') |
+---------------------------+
| aaabbbccc |
+---------------------------+
1 row in set (0.02 sec)
mysql> select insert('beijng2008you',12,3,'me');
+-----------------------------------+
| insert('beijng2008you',12,3,'me') |
+-----------------------------------+
| beijng2008yme |
+-----------------------------------+
1 row in set (0.00 sec)
mysql> SELECT MOD(15,10),MOD(1,11),MOD(null,10);
+------------+-----------+--------------+
| MOD(15,10) | MOD(1,11) | MOD(null,10) |
+------------+-----------+--------------+
| 5 | 1 | NULL |
+------------+-----------+--------------+
1 row in set (0.01 sec)
mysql> select rand(),rand();
+---------------------+--------------------+
| rand() | rand() |
+---------------------+--------------------+
| 0.08019654553401893 | 0.8553781629124453 |
+---------------------+--------------------+
1 row in set (0.01 sec)
mysql> select curdate();
+------------+
| curdate() |
+------------+
| 2018-09-11 |
+------------+
1 row in set (0.00 sec)
mysql> select curtime();
+-----------+
| curtime() |
+-----------+
| 11:11:12 |
+-----------+
1 row in set (0.00 sec)
mysql> select now();
+---------------------+
| now() |
+---------------------+
| 2018-09-11 11:11:21 |
+---------------------+
1 row in set (0.00 sec)