Keys

Repair the Reference

Adding the missing parent row repairs the link.

highlighted = computed this step

Repair the reference

Adding the missing parent row turns the dangling child value into a matched link.

add the parent row\text{add the parent row}

Check again

After repair, dangling-reference count is 0, and valid is yes.

dangling=0\text{dangling}=0

Key examples are tiny finite table checks; SQL dialects, indexing, query planning, deferrable constraints, enforcement timing, performance, and product behavior are out of scope.

Repair the reference: parent tablecustomer_idname1Ada2Ben9Nia Repair the reference: child tableorder_idcustomer_idtotal101150104940 key columnsparent keychild foreign keycustomer_idcustomer_id child-to-parent linkschildRowchildValueparentRowsstatus01[0]match19[2]match duplicate parent keysvalueparentRowsnonenone dangling referenceschildRowvaluestatusnonenonenone key factsfactvalueparentRowCount3childRowCount2duplicateParentKeyCount0referenceCount2danglingReferenceCount0parentKeyUniqueyesvalidyesdeleteStatusnone

Compare the link table

The formerly missing child value now points to one parent row.

one matching parent\text{one matching parent}

Summary

The repair is visible in the exact rows, not described as a hidden database action.

visible repair\text{visible repair}