create database test1 with log;
Database created.


create table aaa.t1(a integer)
Table created.


create table bbb.t1(a integer);
   310 : Table (bbb.t1) already exists in database.


select * from aaa.t1;
          a 
No rows found.


select * from t1;
          a 
No rows found.


select * from "t1";
   201 : A syntax error has occurred.


есть переменная DELIMIDENT=y, которая включает возможность заключать имена идентификаторов в кавычки.
export DELIMIDENT=y


create table aaa."T1"(a integer);
Table created.


select * from "t1";
          a 
No rows found.


---------------------------------------------------------------
create database test2 with log mode ansi;
Database created.


create table aaa.t1(a integer);
Table created.


create table bbb.t1(a integer);
Table created.


create table "Aaa".t1(a integer);
Table created.


create table "aAa"."T1"(a integer);
Table created.

echo "select owner, tabname from systables where lower(tabname) = 't1' "|dbaccess test2

Database selected.




owner    AAA
tabname  t1

owner    BBB
tabname  t1

owner    Aaa
tabname  t1

owner    aAa
tabname  T1

owner    aaa
tabname  T1

owner    aaa
tabname  t1

 6  row(s) retrieved.



Data committed.


Database closed.

informix@nag:~> echo "create table \"T2\"(a integer)"|dbaccess test2

Database selected.


Table created.



Data committed.


Database closed.

informix@nag:~> echo "create table \"t2\"(a integer)"|dbaccess test2

Database selected.


Table created.



Data committed.


Database closed.

echo "create table ccc.t4(a integer)"|dbaccess test2
Table created.

informix@nag:~> echo "select * from t4"|dbaccess test2
   206 : The specified table (informix.t4) is not in the database.
   111 : ISAM error:  no record found.
Database closed.

informix@nag:~> echo "create table ccc.t4(a integer)"|dbaccess test1
Table created.

informix@nag:~> echo "select * from t4"|dbaccess test1
          a 
No rows found.