Method 1 of Oracle cross-database query and replication table data: currently, most databases require distributed query. The following describes how to configure cross-database access in oracle. For example, there are two database servers and two databases are installed. Database server A and B. Now, database A accesses database B. Step 1: Configure tnsnames on server. ora file (TNSNAMES. ORA Network Configuration File), where the File is stored: $ ORACLE_HOME/network/admin/tnsnames. ora needs to add configuration items for database B in this file. The format is ZBCDB3 = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP) (HOST = 10.1.50.6) (PORT = 1523) (CONNECT_DATA = (SERVICE_NAME = zbcdb3) if another client in database A accesses database B, at the same time, you should modify the corresponding files of the client. Step 2: create A data DBLINK for B in A database of server. Syntax: create database link dcmdb connect to dcmdb identified by dcmoptr using 'zbcdb3'; then you can implement distributed query: select * from where 1 = 1; Method 2: first create a database link: create public database link Data LINK name connect to login username identified by password USING (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP) (HOST = ip address of the other Oracle Server) (PORT = PORT number) (CONNECT_DATA = (SERVICE_NAME = service name of the target Oracle Server) 'the Data Link name is added to the local Oracle Database Console (Oracle Enterprise Manager Console) the TableName statement for the service name of the Tree node to query the table of the other database is as follows: SELECT field name FROM TableName @ Data Link name; copy table data: insert into Table Name (field name) (SELECT field name FROM TableName @ Data Link name );