SQL> select 'xxxx'oooo' from dual; ERROR: ORA-01756: quoted string not properly terminated SQL> select "xxxx'oooo" from dual; select "xxxx'oooo" from dual * ERROR at line 1: ORA-00904: "xxxx'oooo": invalid identifier SQL> select q'[xxxx'oooo]' from dual; Q'[XXXX'O --------- xxxx'oooo