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正常情况下，一个事务只能跑在一个数据库上，也就是type-1 connect 。 但DB2支持type-2 connect,也就是一个事务中可以同时连接两个数据库。本文就是type-2连接的测试。

1.）一些说明

 1.1 在被连接的两个数据库中，只能有一个是active状态，另一个是dormant状态。

 1.2 一些关键字的解释与说明

1.   The CONNECT TO <dbname> or CONNECT TO <dbname> USER userid USING password statements establish a connection.
2.   The SET CONNECTION <dbname> statement changes the state of a database connection from dormant to current. It makes the specified location the current server.
3.   The RELEASE statement places one or more connections in the release-pending state.Note that, even though a database has been placed in release pending state,      you may still CONNECT TO or SET  CONNECTION to the database before the COMMIT
4.   The DISCONNECT statement destroys one or more connections when there is no active unit of work (after COMMIT or ROLLBACK WORK).

$ db2set DB2OPTIONS=+c
$ db2stop
$ db2start$ db2 "set client syncpoint twophase connect 2 sqlrules STD"$ db2 "connect to DB1"数据库连接信息数据库服务器         = DB2/NT 10.5.1SQL 授权标识         = QINGSONG本地数据库别名       = DB1$ db2 "select * from t1"ID          NAME
----------- ----------1 AA2 bb2 条记录已选择。$ db2 "update t1 set name='aa' where ID=1"

$ db2 "connect to DB2"数据库连接信息数据库服务器         = DB2/NT 10.5.1SQL 授权标识         = QINGSONG本地数据库别名       = DB2$ db2 "select * from employee"AGE
-----------6872261004 条记录已选择。$ db2 "insert into employee values(300)"

$ db2 "set connection db1"数据库连接信息数据库服务器         = DB2/NT 10.5.1SQL 授权标识         = QINGSONG本地数据库别名       = DB1$ db2 "select * from t1"ID          NAME
----------- ----------1 aa2 bb2 条记录已选择。$ db2 "select * from employee"
SQL0204N  "QINGSONG.EMPLOYEE" 是一个未定义的名称。  SQLSTATE=42704  

$ db2 "release all"
DB20000I  SQL RELEASE 命令成功完成。$ db2 "commit"
DB20000I  SQL 命令成功完成。$ db2 "list applications"
SQL1611W  “数据库系统监视器”没有返回任何数据。