/// <summary>
        /// 访问CAST AS表达式。
        /// </summary>
        /// <param name="explicitCastExpression">表达式。</param>
        /// <returns>返回访问后的表达式实例对象。</returns>
        public Expression VisitExplicitCast(ExplicitCastExpression explicitCastExpression)
        {
            _builder.Append("CAST(");

            Visit(explicitCastExpression.Operand);

            _builder.Append(" AS ");

            var typeMapping = _typeMapper.GetMapping(explicitCastExpression.Type);

            if (typeMapping == null)
            {
                throw new InvalidOperationException(string.Format(Resources.UnsupportedType, explicitCastExpression.Type.DisplayName(false)));
            }

            _builder.Append(typeMapping);

            _builder.Append(")");
            return(explicitCastExpression);
        }