连例复制mysql> select * from t_users;   +---------+-----------+---------+---------------------+   | iUserID | sUserName | iStatus | dtLastTime |   +---------+-----------+---------+---------------------+   | 1 | baidu | 0 | 2010-06-27 15:04:03 |   | 2 | google | 0 | 2010-06-27 15:04:03 |   | 3 | yahoo | 0 | 2010-06-27 15:04:03 |   | 4 | tencent | 0 | 2010-06-27 15:04:03 |   +---------+-----------+---------+---------------------+mysql> select * from t_groups;   +----------+------------+---------------------+   | iGroupID | sGroupName | dtLastTime |   +----------+------------+---------------------+   | 1 | spring | 2010-06-27 15:04:03 |   | 2 | summer | 2010-06-27 15:04:03 |   | 3 | autumn | 2010-06-27 15:04:03 |   | 4 | winter | 2010-06-27 15:04:03 |   +----------+------------+---------------------+mysql> select * from t_users_groups;   +---------+----------+---------------------+   | iUserID | iGroupID | dtLastTime |   +---------+----------+---------------------+   | 1 | 1 | 2010-06-27 15:04:03 |   | 2 | 1 | 2010-06-27 15:04:03 |   | 4 | 3 | 2010-06-27 15:04:03 |   | 6 | 4 | 2010-06-27 15:04:03 |   +---------+----------+---------------------+1.交叉连接   1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25.

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