Question

由于某种原因，我的运行计数列在任何地方返回460，这是我表中第一个邮政编码的总体人口值的总和（在4个不同的邮政编码中）。

有人可以告诉我我的代码有什么问题吗？感谢：

SELECT
target_postcodes.target_postcode as carehome,
population_postcodes.population_postcode as postcodes,
population_postcodes.population as over85,
SQR( (Population_postcodes.Longitude - target_postcodes.longitude)^2 + (Population_postcodes.Latitude - target_postcodes.latitude)^2 ) as distance,
(SELECT sum (population_postcodes.population) as runningcount from population_postcodes) AS runningcount

INTO
cooltable2

FROM
Population_postcodes, Target_postcodes

GROUP BY
target_postcodes.target_postcode,
population_postcodes.population_postcode,
population_postcodes.population,
SQR( (Population_postcodes.Longitude - target_postcodes.longitude)^2 + (Population_postcodes.Latitude - target_postcodes.latitude)^2 )

ORDER BY
SQR( (Population_postcodes.Longitude - target_postcodes.longitude)^2 + (Population_postcodes.Latitude - target_postcodes.latitude)^2 );

由于

Answer 1

您需要添加一个连接条件，指示一个表的哪些行属于另一个表的哪些行。

Answer 2

两项：

1）sum（）函数应用于population_postcodes表上的子查询，该表按条件使所有组无效。

2）没有连接两个表的子句Population_postcodes，Target_postcodes

查询可能应该是...... .... / / p>

   SELECT
      b.target_postcode as carehome,
      a.population_postcode as postcodes,
      a.population as over85,
      SQR( (a.Longitude - b.longitude)^2 + (a.Latitude - b.latitude)^2 ) as distance,
      sum (a.population) as runningcount
   INTO
      cooltable2
   FROM
      Population_postcodes a, Target_postcodes b
   GROUP BY
      b.target_postcode,
      a.population_postcode,
      a.population,
      SQR( (a.Longitude - b.longitude)^2 + (a.Latitude - b.latitude)^2 )
   ORDER BY
      SQR( (a.Longitude - b.longitude)^2 + (a.Latitude - b.latitude)^2 )

子查询不起作用

2 个答案: