C:\Program Files (x86)\Hand\FB25\bin>isql
Use CONNECT or CREATE DATABASE to specify a database
SQL> CREATE DATABASE 'C:\TEMP\D.FDB';
SQL>
SQL> CREATE VIEW V(F1, F2) AS
CON> SELECT RDB$SECURITY_CLASS, COALESCE(RDB$SECURITY_CLASS , 'B') FROM RDB$DATABASE WHERE 1=0;
SQL>
SQL> SET LIST ON;
SQL>
SQL> SELECT * FROM V;
SQL>
-- ничего нет, нормально
SQL> SELECT 1, V.F1, V.F2
CON> FROM RDB$DATABASE LEFT JOIN V ON 1=0;

CONSTANT                        1
F1                              <null>
F2                              B --????? 
SQL>
SQL> SHOW VERSION;
ISQL Version: WI-V2.5.5.26937 Firebird 2.5
Server version: Firebird/x86-64/Windows NT (access method), version "WI-V2.5.5.26937 Firebird 2.5"
Firebird/x86-64/Windows NT (remote server), version "WI-V2.5.5.26937 Firebird 2.5/XNet (***)/P12"
Firebird/x86-64/Windows NT (remote interface), version "WI-V2.5.5.26937 Firebird 2.5/XNet (***)/P12"
on disk structure version 11.2
SQL>

SQL> SET LIST ON;
SQL> SELECT 1, V.F1, V.F2
CON> FROM RDB$DATABASE LEFT JOIN V ON 1=0;

CONSTANT                        1
F1                              <null>
F2                              <null>


SQL> SHOW VERSION;
ISQL Version: WI-V2.5.5.26937 Firebird 2.5
Server version:Firebird/x86-64/Windows NT (access method), version "WI-V2.5.2.26539 Firebird 2.5"
Firebird/x86-64/Windows NT (remote server), version "WI-V2.5.2.26539 Firebird 2.5/tcp (***)/P12"
Firebird/x86-64/Windows NT (remote interface), version "WI-V2.5.5.26937 Firebird 2.5/tcp (***)/P12"
on disk structure version 11.2
SQL>