Class SQLPreparedQueryFn

  • All Implemented Interfaces:
    Callable, Function, GroundedValue, Item, Sequence

    public class SQLPreparedQueryFn
    extends SystemFunction
    This class implements the sql:prepared-query() extension function. Arguments:
    1. The connection
    2. A SQL select statement, typically containing "?" placeholders

    The result is a function, with arity equal to the number of placeholders. When calling this function, the supplied arguments substitute for the placeholders in the query, and the result is a sequence of maps containing the rows selected by the query.

    • Constructor Detail

      • SQLPreparedQueryFn

        public SQLPreparedQueryFn()
    • Method Detail

      • call

        public Function call​(XPathContext context,
                             Sequence[] arguments)
                      throws XPathException
        Description copied from interface: Callable
        Call the Callable.
        context - the dynamic evaluation context
        arguments - the values of the arguments, supplied as Sequences.

        Generally it is advisable, if calling iterate() to process a supplied sequence, to call it only once; if the value is required more than once, it should first be converted to a GroundedValue by calling the utility method SequenceTool.toGroundedValue().

        If the expected value is a single item, the item should be obtained by calling Sequence.head(): it cannot be assumed that the item will be passed as an instance of Item or AtomicValue.

        It is the caller's responsibility to perform any type conversions required to convert arguments to the type expected by the callee. An exception is where this Callable is explicitly an argument-converting wrapper around the original Callable.

        the result of the evaluation, in the form of a Sequence. It is the responsibility of the callee to ensure that the type of result conforms to the expected result type.
        XPathException - if a dynamic error occurs during the evaluation of the expression
      • makePreparedQueryFunction

        public static Expression makePreparedQueryFunction​(java.lang.String tableName,
                                                           Expression predicate)
      • makeWhereClause

        public static boolean makeWhereClause​(Expression predicate,
                                              java.lang.StringBuilder sb,
                                              java.util.List<Expression> params)