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
Tag: FILTER clause
How to use SQL PIVOT to Compare Two Tables in Your Database
This can happen ever so easily. You adapt a table by adding a new column: ALTER TABLE payments ADD code NUMBER(3); You go on, implementing your business logic - absolutely no problem. But then, later on (perhaps in production), some batch job fails because it makes some strong assumptions about data types. Namely, it assumes … Continue reading How to use SQL PIVOT to Compare Two Tables in Your Database
The Awesome PostgreSQL 9.4 / SQL:2003 FILTER Clause for Aggregate Functions
Sometimes when aggregating data with SQL, we'd love to add some additional filters. For instance, consider the following world bank data: GDP per capita (current US$) 2009 2010 2011 2012 CA 40,764 47,465 51,791 52,409 DE 40,270 40,408 44,355 42,598 FR 40,488 39,448 42,578 39,759 GB 35,455 36,573 38,927 38,649 IT 35,724 34,673 36,988 33,814 … Continue reading The Awesome PostgreSQL 9.4 / SQL:2003 FILTER Clause for Aggregate Functions