Module org.jooq
Package org.jooq.impl

Interface QOM.Cardinality

All Superinterfaces:
Field<Integer>, FieldOrConstraint, FieldOrRow, FieldOrRowOrSelect, GroupField, Named, OrderField<Integer>, QueryPart, SelectField<Integer>, SelectFieldOrAsterisk, Serializable, TableElement, Typed<Integer>
Enclosing class:
QOM

public static interface QOM.Cardinality extends Field<Integer>
The CARDINALITY function.

Calculate the cardinality of an array field.

  • Method Details Link icon

    • $array Link icon

      @NotNull default @NotNull Field<? extends Object[]> $array()
    • $array Link icon

      @CheckReturnValue @NotNull default @NotNull QOM.Cardinality $array(Field<? extends Object[]> newArray)
    • $arg1 Link icon

      Field<? extends Object[]> $arg1()
    • $arg1 Link icon

      @CheckReturnValue @NotNull default QOM.Cardinality $arg1(Field<? extends Object[]> newArg1)
    • $constructor Link icon

      @NotNull @NotNull Function1<? super Field<? extends Object[]>,? extends QOM.Cardinality> $constructor()
    • $args Link icon

      @NotNull default @NotNull List<?> $args()
    • $traverse Link icon

      default <T> T $traverse(Traverser<?,T> traverser)
      Description copied from interface: QueryPart
      Traverser this QueryPart expression tree using a composable Traverser, producing a result.

      This offers a generic way to traverse expression trees to translate the tree to arbitrary other data structures. The simplest traversal would just count all the tree elements:

      
       int count = CUSTOMER.NAME.eq(1).$traverse(0, (i, p) -> i + 1);
       

      The same can be achieved by translating the JDK Collector API to the Traverser API using Traversers.collecting(Collector).

      
       CUSTOMER.NAME.eq(1).$traverse(Traversers.collecting(Collectors.counting()));
       

      Unlike a Collector, a Traverser is optimised for tree traversal, not stream traversal:

      • Is not designed for parallelism
      • It can Traverser.abort() traversal early when the result can be produced early (e.g. when running Traversers.containing(QueryPart), and a result has been found).
      • It can decide whether to Traverser.recurse() into a QueryPart subtree, or whether that is not necessary or even undesirable, e.g. to prevent entering new subquery scopes.
      • Unlike a Collector, which can use its Collector.accumulator() to accumulate each element only once, in tree traversal, it's desirable to be able to distinguish between accumulating an item Traverser.before() or Traverser.after() recursing into it. This is useful e.g. to wrap each tree node in XML opening and closing tags.

      This is a commercial jOOQ edition only feature.

      Specified by:
      $traverse in interface QueryPart
    • $replace Link icon

      @NotNull default QueryPart $replace(Replacer replacer)
      Description copied from interface: QueryPart
      Traverse a QueryPart hierarchy and recursively replace its elements by alternatives.

      While replacing contents, this QueryPart isn't modified. Instead, a new object is returned.

      This is a commercial jOOQ edition only feature.

      Specified by:
      $replace in interface QueryPart