postgresql选择进入

Question

我正在尝试创建postgres脚本但是我遇到了从表行的max（）函数insead返回值的麻烦。

这是剧本的重要部分：

  unsigned int key = time(nullptr);
  for (; key > 0; --key)
  {
      srand(key);
      if (rand() == target1 and rand() == target2) {
      std::cout << "key is 0x" << std::hex << key << std::endl;
      break;
      }
  }
  if (key == 0) {
      std::cout << "key not found" << std::endl;
  }

我收到此错误：无效的类型名称“max（bag_index）INTO index FROM booking_bags                     出价“ 第6行：SELECT max（bag_index）INTO index FROM bo ...

任何人都知道如何将值从max函数转换为声明的变量？

Answer 1

            DECLARE @index SMALLINT;
            SELECT @index = max(bag_index) FROM booking_bags 
            WHERE bid = NEW.bid AND 
                  pid = NEW.pid AND 
                  fid = NEW.fid AND 
                  ordered_bag_id = NEW.ordered_bad_id;