Decode equivalent in postgres
There is an equivalent. It's called a CASE statement.
There are two forms of CASE:
Simple CASE:
CASE search-expression WHEN expression [, expression [ ... ]] THEN statements [ WHEN expression [, expression [ ... ]] THEN statements ... ] [ ELSE statements ]END CASE;Searched CASE:
CASE WHEN boolean-expression THEN statements [ WHEN boolean-expression THEN statements ... ] [ ELSE statements ]END CASE;CASE statements are easier to read; I prefer these over decode() in Oracle.
If you are used to Oracle specific functions, you might want to install PostgreSQL extension orafce.
Among other Oracle specific functions, orafce also implements DECODE - one that you are looking for.
If you are running on Ubuntu, you will simply need to install package postgresql-9.1-orafce to make orafce available in your PostgreSQL server.
You can combine NULLIF with COALESCE:
SELECT COALESCE(NULLIF(value, 0), newValue) FROM table;