The structure of the SELECT querySelect-listSQL expressionsDISTINCTFROM clauseSelecting from multiple tablesSelf-joinsWHERE clauseComparison operatorsPattern matchingRow and array comparison constructsGrouping and aggregationGROUP BY clauseHAVING clauseOrdering and limiting the resultsSubqueriesSet operations – UNION, EXCEPT, and INTERSECTDealing with NULLs