COALESCE function in SQL

The COALESCE function can be used in Oracle/PLSQL.

You could use the coalesce function in a SQL statement as follows:

SELECT COALESCE( address1, address2, address3 ) result FROM suppliers;

The above COALESCE function is equivalent to the following IF-THEN-ELSE statement:

IF address1 is not null THEN
   result := address1;

ELSIF address2 is not null THEN
   result := address2;

ELSIF address3 is not null THEN
   result := address3;

ELSE
   result := null;

END IF;

The COALESCE function will compare each value, one by one.