Question

如何从sqlite中的另一个select执行复合select语句？是否可以使用select？

中的计算列在WHERE子句中添加条件

我有以下工作声明

SELECT detection_id,
      evalround_id,
      min(detection.posright, labelgt.posright) - max(detection.posleft, labelgt.posleft) + 1 
        AS overlap_width
FROM detection, labelgt
WHERE 
      labelgt.timestamp = detection.timestamp

我想在计算的'overlap_width'

上添加条件

 AND overlap_width > 0

不幸以错误结束'执行查询时出错：没有这样的列：overlap_width'。

我尝试创建一个复合语句，

SELECT
    *
    FROM
        (
         SELECT  detection_id,
              evalround_id,
              min(detection.posright, labelgt.posright) - max(detection.posleft, labelgt.posleft) + 1 
                AS overlap_width
            -- overlap_width * overlap_height AS overlap_area
        FROM detection, labelgt
        WHERE 
                labelgt.timestamp = detection.timestamp 
        ) AS IT
    WHERE
        IT.overlap_width > 0

在执行查询时出现'错误：没有这样的列：detection.posleft'。但是表格中有一个有效的列检测.posleft。

Answer 1

SQLite支持它，你可以在你的内部列上有条件。即。

SELECT * FROM (select min(b.cold1-c.col2) as tid, *  from table1 b , table2 c )   where tid =  -538

SqLite composite从Select语句中选择

1 个答案: