JOIN USING

Matched Rows

Equal non-NULL keys become output rows.

highlighted = computed this step

Matched rows

Each matching pair becomes one JOIN USING output row.

matched output\text{matched output}

Read matched rows

The join emits 5 matched rows.

output rows=5\text{output rows}=5

JOIN USING examples are tiny finite-table transforms; SQL dialect completeness, type coercion, optimizer behavior, execution cost, indexing, output ordering guarantees, and database-product claims are out of scope.

Matched rows: left tableorder_idcustomer_idnote110new220rush320gift4NULLdraft Matched rows: right tablecustomer_idnamenote10Adavip20Benstandard20Bennyduplicate30CyprospectNULLUnknownmissing candidate key comparisonsleftSourcerightSourceleftKeyrightKeymatched001010yes011020no021020no031030no0410NULLno102010no112020yes122020yes132030no1420NULLno202010no212020yes222020yes232030no2420NULLno30NULL10no31NULL20no32NULL20no33NULL30no34NULLNULLno JOIN USING output rowscustomer_idleft.order_idleft.noteright.nameright.note101newAdavip202rushBenstandard202rushBennyduplicate203giftBenstandard203giftBennyduplicate ON join contrast rowsleft.order_idleft.customer_idleft.noteright.customer_idright.nameright.note110new10Adavip220rush20Benstandard220rush20Bennyduplicate320gift20Benstandard320gift20Bennyduplicate JOIN USING factsfactvalueleftRowCount4rightRowCount5candidatePairCount20matchingPairCount5matchedLeftRows3duplicateMatchRows2nullKeyCandidatePairs8usingKeyAppearsOnceyesduplicateNonKeyNames[note]outputColumnCount5onOutputColumnCount6rowOrderleft_source_then_right_source

Bag-style rows

Rows are not deduplicated after matching.

no implicit DISTINCT\text{no implicit DISTINCT}

Summary

JOIN USING is still an inner join for which rows survive.

inner join survival\text{inner join survival}