CASE Expressions

No ELSE Gives NULL

No match and no ELSE returns NULL.

highlighted = computed this step

No ELSE gives NULL

If no branch is TRUE and there is no ELSE, CASE returns NULL.

implicit NULL\text{implicit NULL}

Read implicit NULL rows

No ELSE produces 3 NULL result rows.

implicit NULL rows=3\text{implicit NULL rows}=3

CASE-expression examples are tiny finite row transforms with SQL-style TRUE/FALSE/UNKNOWN logic; SQL dialect completeness, type coercion, optimizer behavior, indexing, and product claims are out of scope.

No ELSE gives NULL: base rowsnamescorestatusAda90activeBea40activeCalNULLactiveDee70paused CASE branch evaluationsourcevaluesevaluationsresultresultSource0[Ada, 90, active][{branch:0, truth:TRUE, chosen:yes}]highbranch 01[Bea, 40, active][{branch:0, truth:FALSE, chosen:no}]NULLimplicit NULL2[Cal, NULL, active][{branch:0, truth:UNKNOWN, chosen:no}]NULLimplicit NULL3[Dee, 70, paused][{branch:0, truth:FALSE, chosen:no}]NULLimplicit NULL CASE output rowsnamescorestatusbucketAda90activehighBea40activeNULLCalNULLactiveNULLDee70pausedNULL CASE factsfactvalueinputRowCount4branchCount1outputRowCount4firstTrueRows1elseRows3nullElseRows3unknownSkipped1rowOrdersource_order

No hidden default

The compiler does not invent a label when ELSE is absent.

no hidden default\text{no hidden default}

Summary

No match and no ELSE means NULL.

CASE result NULL\text{CASE result NULL}