select 'hello' greeting from dual; | :   | Simple echo with pseudo-table |
select sysdate from dual; | :   | Returns current date |
select lower('500 REDWOOD SHORES') from dual; | :   |
Address in lowercase |
select abs(-100) "plus or minus" from dual; | :   | Returns constant |
select compose('o'||unistr('\0308')) "umlaut" from dual; | :   | Umlaut o |
select extract(year from date '2005-01-08') as year from dual; | :   | Returns datetime field value |
select rowid,rownum from dept; | :   | ID & ordering pseudo-columns |
select to_char(to_date('02-08-2005','MM-DD-YYYY'),'J') from dual; | :   | Julian conversion |
select myseq.currval,myseq.nextval from dual; | :   | Sequence values |
select level...start with...connect by... | :   | Hierarchical pseudo-column |