日期:2014-05-16 浏览次数:20857 次
>mysql -h localhost -u root -p
mysql> use world; Database changed mysql> show tables; +-----------------+ | Tables_in_world | +-----------------+ | city | | country | | countrylanguage | +-----------------+ 3 rows in set (0.00 sec)
mysql> select count(*) from city; +----------+ | count(*) | +----------+ | 4079 | +----------+ 1 row in set (0.00 sec)
mysql> select count(*) from country; +----------+ | count(*) | +----------+ | 239 | +----------+ 1 row in set (0.00 sec)
mysql> select 4079*239
-> ;
+----------+
| 4079*239 |
+----------+
| 974881 |
+----------+
1 row in set (0.00 sec)mysql> select count(*) from city,country
-> ;
+----------+
| count(*) |
+----------+
| 974881 |
+----------+
1 row in set (0.00 sec)mysql> select count(*) from city,country,countrylanguage; +-----------+ | count(*) | +-----------+ | 959282904 | +-----------+ 1 row in set (0.02 sec) mysql> select count(*) from countrylanguage; +----------+ | count(*) | +----------+ | 984 | +----------+ 1 row in set (0.00 sec) mysql> select 4079*239*984; +--------------+ | 4079*239*984 | +--------------+ | 959282904 | +--------------+ 1 row in set (0.00 sec)