The problem that sap hana, oracle, and postgresql cannot be remotely connected

The failure to remotely connect to sap hana, oracle, and postgresql has recently been useful to these three databases. 1. sap hana is installed on the opensuse system. Generally, it cannot be connected remotely because the database service is not enabled. Switch to the hana user on linux and enable the Service by running the HDB start command. 2. when oracle cannot be remotely connected, it may be that the listening service is not enabled or the database service is not started. First, switch to the oracle user on the remote host and use sqlplus/as sysdba to access the database as an administrator, run the startup command to restart the database and start the instance. Then exit and run the command lsnrctl start in the operating system to enable the listening service. 3. when postgreSQL cannot be remotely connected, run the command/usr/local/pgsql/bin/postmaster-D/usr/local/pgsql/data to restart the service. Of course, it is also under postgreSQL users. In postgresql, the configuration files for remote connection are actually in postgresql. conf and pg_assist.conf.