Query-expressions are called subqueries when used in WHERE or HAVING clauses. A subquery is a query-expression that is nested as part of another query-expression. A subquery selects one or more rows ...

When you execute a query using the LEFT JOIN syntax, SQL does two things: It returns all of the records from both tables that contain matching values, as defined by the ON clause.

PROC SQL provides traditional set operators from relational algebra: OUTER UNION concatenates the query results. UNION produces all unique rows from both queries. EXCEPT produces rows that are part of ...