Alibabacloud, Database, Query Optimization, Sql, Relational Databases.
“exists/in” subqueries, correlated subqueries can also be used in the where clause as values required for filtering conditions. For example, tpch q17 below uses subqueries to obtain an aggregation value as the filtering condition. -- tpch q17 SELECT Sum(l1.extendedprice) / 7.0 AS avg_yearly FROM