How to use

com.facebook.presto.sql.tree.NullIfExpression

constructor

return new NullIfExpression(toExpression(first, firstType), toExpression(second, secondType));

check(!filter.isPresent(), "FILTER not valid for 'nullif' function", context);
return new NullIfExpression(
    getLocation(context),
    (Expression) visit(context.expression(0)),

@Test
public void testNullIf()
{
  assertExpression("nullif(42, 87)", new NullIfExpression(new LongLiteral("42"), new LongLiteral("87")));
  assertExpression("nullif(42, null)", new NullIfExpression(new LongLiteral("42"), new NullLiteral()));
  assertExpression("nullif(null, null)", new NullIfExpression(new NullLiteral(), new NullLiteral()));
  assertInvalidExpression("nullif(1)", "Invalid number of arguments for 'nullif' function");
  assertInvalidExpression("nullif(1, 2, 3)", "Invalid number of arguments for 'nullif' function");
  assertInvalidExpression("nullif(42, 87) filter (where true)", "FILTER not valid for 'nullif' function");
  assertInvalidExpression("nullif(42, 87) OVER ()", "OVER clause not valid for 'nullif' function");
}

@Test
public void testExpressionsThatMayReturnNullOnNonNullInput()
{
  List<Expression> candidates = ImmutableList.of(
      new Cast(nameReference("b"), "BIGINT", true), // try_cast
      new FunctionCall(QualifiedName.of("try"), ImmutableList.of(nameReference("b"))),
      new NullIfExpression(nameReference("b"), number(1)),
      new IfExpression(nameReference("b"), number(1), new NullLiteral()),
      new DereferenceExpression(nameReference("b"), identifier("x")),
      new InPredicate(nameReference("b"), new InListExpression(ImmutableList.of(new NullLiteral()))),
      new SearchedCaseExpression(ImmutableList.of(new WhenClause(new IsNotNullPredicate(nameReference("b")), new NullLiteral())), Optional.empty()),
      new SimpleCaseExpression(nameReference("b"), ImmutableList.of(new WhenClause(number(1), new NullLiteral())), Optional.empty()),
      new SubscriptExpression(new ArrayConstructor(ImmutableList.of(new NullLiteral())), nameReference("b")));
  for (Expression candidate : candidates) {
    EqualityInference.Builder builder = new EqualityInference.Builder();
    builder.extractInferenceCandidates(equals(nameReference("b"), nameReference("x")));
    builder.extractInferenceCandidates(equals(nameReference("a"), candidate));
    EqualityInference inference = builder.build();
    List<Expression> equalities = inference.generateEqualitiesPartitionedBy(matchesSymbols("b")).getScopeStraddlingEqualities();
    assertEquals(equalities.size(), 1);
    assertTrue(equalities.get(0).equals(equals(nameReference("x"), nameReference("b"))) || equalities.get(0).equals(equals(nameReference("b"), nameReference("x"))));
  }
}

return new NullIfExpression(toExpression(first, firstType), toExpression(second, secondType));

check(!filter.isPresent(), "FILTER not valid for 'nullif' function", context);
return new NullIfExpression(
    getLocation(context),
    (Expression) visit(context.expression(0)),

@Test
public void testNullIf()
{
  assertExpression("nullif(42, 87)", new NullIfExpression(new LongLiteral("42"), new LongLiteral("87")));
  assertExpression("nullif(42, null)", new NullIfExpression(new LongLiteral("42"), new NullLiteral()));
  assertExpression("nullif(null, null)", new NullIfExpression(new NullLiteral(), new NullLiteral()));
  assertInvalidExpression("nullif(1)", "Invalid number of arguments for 'nullif' function");
  assertInvalidExpression("nullif(1, 2, 3)", "Invalid number of arguments for 'nullif' function");
  assertInvalidExpression("nullif(42, 87) filter (where true)", "FILTER not valid for 'nullif' function");
  assertInvalidExpression("nullif(42, 87) OVER ()", "OVER clause not valid for 'nullif' function");
}

check(!distinct, "DISTINCT not valid for 'nullif' function", context);
return new NullIfExpression(
    getLocation(context),
    (Expression) visit(context.expression(0)),