Question

SELECT s1.id, 
       s3.food_name, 
       Count(*) AS TotalRefill 
FROM   (SELECT ( s1.food_value - s2.food_value ) AS difference 
        FROM   `serving_info` s1, 
               `serving_info` s2 
        WHERE  s1.id - s2.id = '1' 
               AND s1.food_name = 'Shrimp' 
               AND s2.food_name = 'Shrimp') AS diff, 
       `serving_info` s3 
WHERE  s3.id = diff.id 
       AND s3.food_value >= '990' 
       AND diff.difference >= '150'

结果：#1054 - Unknown column 's1.id' in 'field list'

--
-- Table structure for table `employees`
--
CREATE TABLE IF NOT EXISTS `employees` (
  `id_user` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(128) NOT NULL,
  `email` varchar(64) NOT NULL,
  `phone_number` varchar(16) NOT NULL,
  `username` varchar(16) NOT NULL,
  `password` varchar(32) NOT NULL,
  `confirmcode` varchar(32) DEFAULT NULL,
  PRIMARY KEY (`id_user`),
  KEY (name)
);
--
-- Table structure for table `Foods`
--
CREATE TABLE IF NOT EXISTS `Foods` (
  `Food_name` varchar(40) NOT NULL,
  `CostPerRefill` double NOT NULL,
  PRIMARY KEY (`Food_name`)
);


--
-- Table structure for table `Serving_Info`
--
CREATE TABLE IF NOT EXISTS `Serving_Info` (
  `id` int(255) NOT NULL AUTO_INCREMENT,
  `Food_Value` varchar(40) NOT NULL,
  `Food_name` varchar(40) NOT NULL,
  `Served_On` TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
  `Oncall` varchar(128),
  Foreign key(`Oncall`) REFERENCES `employees`(`name`),
  Foreign key(`Food_name`) REFERENCES `Foods`(`Food_name`),
  PRIMARY KEY (`id`),
  UNIQUE (`Oncall`,`Food_name`, `Served_On`)
);

是什么导致s1不被声明？由于某种原因，s1.id没有检测到s1实例。我一直试图通过改变不同的括号来解决这个问题，但我真的无法弄清楚如何调试这个..我试过改变关闭括号的位置，但这会弄乱查询。

Answer 1

这里所有其他人说的是正确的，但只是为了给你一个更优先的解决方案，看下面的查询它不应该是s1.id但它应该是diff.id

SELECT diff.id, 
       s3.food_name, 
       Count(*) AS TotalRefill 
FROM   (SELECT ( s1.food_value - s2.food_value ) AS difference, s1.id 
        FROM   `serving_info` s1, 
               `serving_info` s2
        WHERE  s1.id - s2.id = '1' 
               AND s1.food_name = 'Shrimp' 
               AND s2.food_name = 'Shrimp') AS diff, 
       `serving_info` s3 
WHERE  s3.id = diff.id 
       AND s3.food_value >= '990' 
       AND diff.difference >= '150'

Answer 2

S1在括号内定义，因此在它们之外不可见，在那里引用它。

Answer 3

因为s1仅在内部选择中定义，所以不是范围。选择diff.id或s3.id（它们将与您加入的值相同）。

Answer 4

表s1不在您尝试选择它的查询的from部分，它只在子查询中。

SQL SELECT查询无效

4 个答案: