DELETE Statements

DELETE Removes TRUE Rows

TRUE rows disappear from the output table.

highlighted = computed this step

DELETE removes TRUE rows

A TRUE row disappears from the output table.

row removed\text{row removed}

Remove one task

The DELETE removes 1 row and keeps 3 rows.

kept=3\text{kept}=3

DELETE examples are tiny finite row removals; SQL dialect completeness, joins in DELETE, subqueries, triggers, constraints, transactions, locks, indexes, optimizer behavior, performance, and product behavior are out of scope.

DELETE removes TRUE rows: base rowsidownerstatuspoints1Adaopen102Benopen203Cydone154DeeNULL5 WHERE chooses rowssourcevaluecompareTotruthremoved012FALSEno122TRUEyes232FALSEno342FALSEno Rows removedsourcerowreason1(2, Ben, open, 20)WHERE_TRUE Rows after DELETEidownerstatuspoints1Adaopen103Cydone154DeeNULL5 DELETE factsfactvaluebaseRowCount4removedRowCount1keptRowCount3finalRowCount3whereUnknownCount0deleteStatusremoved_rowswhereKindeq

Read rows removed

The removed-rows table lists the source row that WHERE marked TRUE.

removed row listed\text{removed row listed}

Summary

The after table is the original table minus the removed row.

after table\text{after table}