**Error Code SQLITE_LOCKED (6): Database Id Locked**

This error code occurs when you try to do to incompatible things
with a database at the same time from the same database connection.
For example, if you are in the middle of a SELECT statement and
you try to DROP one of the tables being read by the SELECT, you
will get an SQLITE_LOCKED error.  Here is an example
(using {link: tclsqlite.html Tcl}):

   db eval {SELECT rowid FROM ex1} {
     if {$rowid==10} {
       db eval {DROP TABLE ex1}  ;# will give SQLITE_LOCKED error
     }
   }

Note that an SQLITE_LOCKED error is distinct from SQLITE_BUSY (5).
SQLITE_BUSY means that another database connection (probably in
another process) is using the database in a way that prevents you
from using it.  SQLITE_LOCKED means the source of contention is
internal and comes from the same database connection that received
the SQLITE_LOCKED error.

Here are other reasons for getting an SQLITE_LOCKED error:

1: Trying to CREATE or DROP a table or index while a SELECT statement is
   still pending.

*:: Sometimes people think they have finished with a SELECT statement
   because sqlite3_step() has returned SQLITE_DONE.  But the SELECT
   is not really complete until sqlite3_reset() or sqlite3_finalize()
   have been called.

2: Trying to write to a table while a SELECT is active on that
   same table.

*:: As of check-in [3355] (2006-08-16 after version 3.3.7) this is
    now allowed.