Package org.apache.qpid.server.query.engine.parsing.expression.function.string

Class ConcatExpression<T,​R>

  • Type Parameters:
    T - Input parameter type
    R - Return parameter type
    All Implemented Interfaces:
    Function<T,​String>, Expression<T,​String>, ExpressionNode<T,​String>
    public class ConcatExpression<T,​R>
extends AbstractFunctionExpression<T,​String>
    CONCAT takes a variable number of arguments and concatenates them into a single string. It requires a minimum of one input value, otherwise CONCAT will raise an error. CONCAT implicitly converts all arguments to string types before concatenation. The implicit conversion to strings follows the existing rules for data type conversions. If any argument is NULL, CONCAT returns an empty string.

    • Constructor Detail

      • ConcatExpression

        public ConcatExpression​(String alias,
                        List<ExpressionNode<T,​?>> args)
        Constructor initializes children expression list
        Parameters:
        alias - Expression alias
        args - List of children expressions

    • Method Detail

      • apply

        public String apply​(T value)
        Performs concatenation operation using parameters and the value supplied
        Parameters:
        value - Object to handle
        Returns:
        Resulting string