Thank´s Paul,
I try using

EXEC SQL CONNECT db1;
EXEC SQL CONNECT db2;

and GPRE report:

(E) Inconsistent database especifier

The structore of tables is:

TEST1.FDB -> table TEST
ID SMALLINT
NAME CHAR(30)

TEST2.FDB -> table TEST
ID SMALLINT
NAME CHAR(30)

--- In firebird-tools@yahoogroups.com, "eulersmjr" <euler@s...> wrote:
> Hi All,
> This simple embedded sql code, writted in C language, when
> pre-processed with GPRE, display message:
>
> inconsistent database especifier
>
> Exemple:
>
> /*
> db1 and db2 have some tables and structures
> db1 is populated and db2 is empty
> */
>
> EXEC SQL SET DATABASE db1 = "c:\test1.fdb";
> EXEC SQL SET DATABASE db2 = "c:\test2.fdb";
>
> EXEC SQL CONNECT ALL;
> EXEC SQL SET TRANSACTION;
>
> /* TEST is a table from db1 and db2 */
> /* ERROR HERE !! */
> EXEC SQL INSERT INTO db2.TEST SELECT * FROM db1.TEST;
>
> EXEC SQL COMMIT;
> EXEC SQL DISCONNECT ALL;
>
>
> The command line is:
> gpre test.e -c -manual -no_lines -either_case -user sysdba
> -password masterkey
>
>
> Thank´s
> Euler Jr