mysql> SHOW COLUMNS FROM quote;
+--------------+---------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+--------------+---------+------+-----+---------+----------------+
| symbol | char(8) | YES | | NULL | |
| date | date | YES | | NULL | |
| open | double | YES | | NULL | |
| high | double | YES | | NULL | |
| low | double | YES | | NULL | |
| close | double | YES | | NULL | |
| vol | double | YES | | NULL | |
| adj | double | YES | | NULL | |
| id | int(10) | YES | | NULL | |
| new_field_id | int(10) | NO | PRI | NULL | auto_increment |
+--------------+---------+------+-----+---------+----------------+
10 rows in set (0.05 sec)
mysql> select var(high) from quote where symbol='YHOO';
ERROR 1305 (42000): FUNCTION nasdaq.var does not exist
+--------------+---------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+--------------+---------+------+-----+---------+----------------+
| symbol | char(8) | YES | | NULL | |
| date | date | YES | | NULL | |
| open | double | YES | | NULL | |
| high | double | YES | | NULL | |
| low | double | YES | | NULL | |
| close | double | YES | | NULL | |
| vol | double | YES | | NULL | |
| adj | double | YES | | NULL | |
| id | int(10) | YES | | NULL | |
| new_field_id | int(10) | NO | PRI | NULL | auto_increment |
+--------------+---------+------+-----+---------+----------------+
10 rows in set (0.05 sec)
mysql> select var(high) from quote where symbol='YHOO';
ERROR 1305 (42000): FUNCTION nasdaq.var does not exist
确实不是MYSQL的函数。
select avg(high) from quote where symbol='YHOO';
这个求平均数。