The COALESCE function returns the first non null expression in the expression list.
COALESCE syntax
COALESCE( expr_1, expr_2, expr_n )
COALESCE example
select COALESCE(null,'1') from dual; Result: 1 select COALESCE(null, 2) from dual; Result: 2 select COALESCE(null, null, 3) from dual; Result: 3 select COALESCE(null, null, null, 4) from dual; Result: 4 select COALESCE(null, null, null, null, 5) from dual; Result: 5 select COALESCE(null, null, 7, null, 5) from dual; Result: 7