Oracle SQL

Turn table rows into well-formed XML elements with XMLELEMENT, add attributes with XMLATTRIBUTES, and create element runs with XMLFOREST.

List every subset of a collection, or only the pairs or triples, with POWERMULTISET and POWERMULTISET_BY_CARDINALITY.

Gather the values of each group into a nested table collection with COLLECT and CAST, and avoid the ORA-00932 element type mismatch.

Remove duplicate elements from a nested table collection, the collection version of DISTINCT, and use it after MULTISET UNION.

Count the elements of a nested table collection in SQL, and see how empty collections, NULL collections, and NULL elements behave.

Translate between container names, container IDs, DBIDs, UIDs, and GUIDs in a container database with the eight CON_ functions.

Format, sort, and validate values by the rules of a data use case domain with DOMAIN_DISPLAY, DOMAIN_ORDER, and DOMAIN_CHECK.

Find out who is logged in, where they connect from, and which module is running, with SYS_CONTEXT and the built-in USERENV context.

Generate random UUIDs, convert between RAW and the hyphenated text form, validate strings, and store UUIDs efficiently as RAW(16).

Compare JSON documents by their content rather than their text, and learn which differences JSON_EQUAL ignores and which it reports.

Replace, add, and delete fields of a JSON document with a merge patch, and learn why arrays are replaced whole and nulls mean delete.

Generate globally unique 16-byte identifiers for keys, use SYS_GUID as a column default, and see when a random UUID is the better choice.

Check whether a JSON document has a field or matches a filter, and pass values into path filters as variables instead of literals.

Avoid ORA-01878 in the spring gap, resolve the repeated autumn hour with TZD, and keep timestamp arithmetic correct across clock changes.

Show dates the way user interfaces do, such as 3 days ago, 6 weeks ago, or in 2 hours, directly in SQL with a long or short form.

Report by the 4-5-4 retail calendar of whole weeks, with retail month and week names and their start and end dates, without a table.

Compute fiscal years, quarters, and period start and end dates for a year that starts in April, October, or any day you choose.

Name the quarter, month, or week of a date, find the first and last day of any period, and move dates by whole periods in one call.