Database view missing from IntelliJ

I wish did fix the issue. I think you're looking for the 'Server Explorer' which is on the view menu. The default key binding is Ctrl+Alt+S

To fix this issue For some reason some databases are not visible in Database View of IntelliJ IDEA. , You should create at least one table in this schema.

wish of those help Right-click on connection -> Properties -> Schemas and Tables tab -> select all the checkboxes in available databases tab -> click OK

Any of those help In this case it's probably easier to just create the table and ignore the SQLException that comes back if the table already exists. Let the DB worry about checking if the table exists already.
For example:

Connection conn = ds.getConnection()
try {
  conn.createStatement().executeUpdate("CREATE TABLE ....");
} finally {
  conn.close();
} catch(SQLException ignore) {
  // ignore exception, not much can go wrong here except for the table already existing.

  // If you don't mind making vendor specific logic, check the error message for "already exists" or some equivalent
  if(!ignore.getMessage().contains("already exists"))
    throw ignore;
}

I hope this helps you . You can still find these classes in historic branches (BytePointer, ClsUtil). They are licensed under Apache 2, so you may just include them into your plugin.
Alternatively, you may rewrite the code using java.io.DataInputStream and ASM classes (org.jetbrains.org.objectweb.asm.Opcodes, org.jetbrains.org.objectweb.asm.Type etc.)