Set Operations

EXCEPT Removes Right Rows

EXCEPT keeps left rows absent from the right.

highlighted = computed this step

EXCEPT removes right rows

EXCEPT keeps left-side row identities that do not appear on the right.

left minus right\text{left minus right}

Remove right-side matches

The result has 1 row.

result rows=1\text{result rows}=1

Set-operation examples are tiny finite bag transforms; SQL dialect details, type coercion, collations, ordering clauses, performance, and product behavior are out of scope.

EXCEPT removes right rows: left input bagidtag1red1red2blue3green EXCEPT removes right rows: right input bagidtag1red3green3green4gold bag countsrowleftCountrightCountresultCount[1, red]210[2, blue]101[3, green]120[4, gold]010 result rowsidtag2blue set operation factsfactvalueopexceptleftRowCount4rightRowCount4resultRowCount1distinctResultRows1rejectednorejectionReasonnonerowOrdercanonical

Read the surviving row

The surviving row has no matching right-side count.

right count is zero\text{right count is zero}

Summary

Plain EXCEPT is distinct in this scoped model.

distinct left remainder\text{distinct left remainder}