Disclaimer: This article is a blogger original article, follow the CC 4.0 BY-SA copyright agreement, reproduced, please attach the original source link and this statement.
oralce function nvl (table_col, b) when the mean how table_col is empty value b, for example, may be blended sum nvl (sum (table_col), b)
select "NVL"(count(cp.id), 0),"NVL"(sum(cp.change_price), 0) from C_CONTRACT_CHANGE_PROTOCOL cp