You need a subquery: select z, avg(sumval) from (select y, z, sum(x) as sumval from t group by y, z ) t group by z. ... <看更多>

DISTINCT ON(). Just as a side note, this is precisely what DISTINCT ON() does (not to be confused with DISTINCT ). SELECT DISTINCT ON ( expression [, . ... <看更多>

Explore the full course - special maximum discount included in this link: https://www.udemy.com/sql-and ... ... <看更多>

PostgreSQL Stats Aggregate (stats_agg). stats_agg is an aggregate function for PostgreSQL that works like pre-existing aggregates ( min(x) , max() , avg() ... ... <看更多>

declaration: module: org.postgresql.pljava, ... An aggregate function in PostgreSQL is defined by using CREATE AGGREGATE to specify its name and argument ... ... <看更多>