Sets the current active database on the given link identifier.
The client contacts FBExec to obtain the port number to use for the connection to the database. If the database name is a number the system will use that as a port number and it will not ask FBExec for the port number. The FrontBase server can be stared as FRontBase -FBExec=No -port=<port number> <database name>.
Every subsequent call to fbsql_query() will be made on the active database.
The name of the database to be selected.
If the database is protected with a database password, the you must call fbsql_database_password() before selecting the database.
If optional and not specified, the function will try to find an open link to the FrontBase server and if no such link is found it will try to create one as if fbsql_connect() was called with no arguments