About manually deleting Oracle data data, causing Oracle to fail to connect the process

First use is using: SYSDBA login Sqlplus/as SYSDBA

In the SQL command line, enter ALTER DATABASE open;

This time it will be reported similar to "ORA-01157: Cannot identify/Lock data file 12-see DBWR trace file ORA-01110: Data file: ' E:\DBF\A.DBF '" error.

This is because the a.dbf file was physically deleted, but the associated record was not deleted in the Oracle system. So what we're going to do next is use "ALTER DATABASE datafile ' E:\DBF\A.DBF ' offline drop;" Statement to delete an associated record from an Oracle system.

Make an ALTER DATABASE open again; Operation, know that no error can be reached.

About manually deleting Oracle data data, causing Oracle to fail to connect the process