A cool standard SQL:2003 feature is the aggregate FILTER clause, which is supported natively by at least these RDBMS: ClickHouse CockroachDB DuckDB Firebird H2 HSQLDB PostgreSQL SQLite Trino YugabyteDB The following aggregate function computes the number of rows per group which satifsy the FILTER clause: SELECT COUNT(*) FILTER (WHERE BOOK.TITLE LIKE 'A%'), COUNT(*) FILTER (WHERE … Continue reading Emulating SQL FILTER with Oracle JSON Aggregate Functions
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