Question

是否有与intersect类似或产生相同结果的内联sql命令？如果没有，是否有办法重写查询，使其在一个查询中而不是使用intersect？

我当前的SQL查询是：

SELECT 
  c.Log_Link 
FROM 
  Classes c INNER JOIN 
  ClassValues cv ON c.Class_Link = cv.Class_Link INNER JOIN 
  ClassSelection cs ON cv.ClassSelection_Link = cs.ClassSelection_Link
WHERE 
  cs.classselection_link IN (95,1)

但我真正追求的是：

SELECT 
  c.Log_Link 
FROM 
  Classes c INNER JOIN 
  ClassValues cv ON c.Class_Link = cv.Class_Link INNER JOIN 
  ClassSelection cs ON cv.ClassSelection_Link = cs.ClassSelection_Link
WHERE 
  cs.classselection_link = 95 
INTERSECT 
SELECT 
  c.Log_Link 
FROM 
  Classes c INNER JOIN 
  ClassValues cv ON c.Class_Link = cv.Class_Link INNER JOIN 
  ClassSelection cs ON cv.ClassSelection_Link = cs.ClassSelection_Link
WHERE 
  cs.classselection_link = 1

由于

Answer 1

可能正在使用内部联接...

SELECT
    *
FROM
    (
        SELECT 
          c.Log_Link 
        FROM 
          Classes c INNER JOIN 
          ClassValues cv ON c.Class_Link = cv.Class_Link INNER JOIN 
          ClassSelection cs ON cv.ClassSelection_Link = cs.ClassSelection_Link
        WHERE 
          cs.classselection_link = 95 
    ) T1
INNER JOIN
    (
        SELECT 
          c.Log_Link 
        FROM 
          Classes c INNER JOIN 
          ClassValues cv ON c.Class_Link = cv.Class_Link INNER JOIN 
          ClassSelection cs ON cv.ClassSelection_Link = cs.ClassSelection_Link
        WHERE 
          cs.classselection_link = 1
    ) T2
ON
    T1.Log_Link = T2.Log_Link

Answer 2

你总是可以这样做：

SELECT DISTINCT
  c.Log_Link 
FROM 
  Classes c INNER JOIN 
  ClassValues cv1 ON c.Class_Link = cv1.Class_Link INNER JOIN 
  ClassSelection cs1 ON cv1.ClassSelection_Link = cs1.ClassSelection_Link

INNER JOIN
  ClassValues cv2 ON c.Class_Link = cv2.Class_Link INNER JOIN 
  ClassSelection cs2 ON cv2.ClassSelection_Link = cs2.ClassSelection_Link

WHERE 
    cs1.classselection_link = 95 
  AND
    cs2.classselection_link = 1

或 GROUP BY ：

SELECT 
  c.Log_Link 
FROM 
  Classes c INNER JOIN 
  ClassValues cv ON c.Class_Link = cv.Class_Link INNER JOIN 
  ClassSelection cs ON cv.ClassSelection_Link = cs.ClassSelection_Link
WHERE 
  cs.classselection_link IN (95,1)
GROUP BY
  c.Class_Link
HAVING
  COUNT(c.Class_Link) = 2

因为你真的不需要ClassSelection表：

SELECT 
  c.Log_Link 
FROM 
  Classes c INNER JOIN 
  ClassValues cv ON c.Class_Link = cv.Class_Link
WHERE 
  cv.ClassSelection_Link IN (95,1)
GROUP BY
  c.Class_Link
HAVING
  COUNT(c.Class_Link) = 2

正如gbn指出的那样，我假设表(Class_Link, ClassSelection_Link)中UNIQUE为ClassValues。

如果不是这样，那么最后2个查询中的HAVING子句应该更改为：

HAVING
  COUNT(DISTINCT cv.ClassSelection_Link) = 2

Answer 3

INTERSECT和EXISTS在语义上是相同的。而且你不需要那么多表

SELECT 
  c.Log_Link 
FROM 
  Classes c
WHERE 
  EXISTS (
      SELECT * FROM ClassValues cv
      WHERE c.Class_Link = cv.Class_Link AND cv.classselection_link = 95)
AND
  EXISTS (
      SELECT * FROM ClassValues cv
      WHERE c.Class_Link = cv.Class_Link AND cv.classselection_link = 1)

Answer 4

我很确定你只想要与众不同。您正在尝试获得一组符合任一条件的唯一c.Log_Link，对吗？如果是这样的话：

SELECT DISTINCT
  c.Log_Link 
FROM 
  Classes c INNER JOIN 
  ClassValues cv ON c.Class_Link = cv.Class_Link INNER JOIN 
  ClassSelection cs ON cv.ClassSelection_Link = cs.ClassSelection_Link
WHERE 
  cs.classselection_link IN (95,1)

编辑：我看到你的澄清了。我认为加入派生表作为amit_g建议是可行的方法。

我稍微调整了一下：

SELECT 
  c.Log_Link 
FROM 
  Classes c INNER JOIN 
  ClassValues cv ON c.Class_Link = cv.Class_Link INNER JOIN 
  ClassSelection cs ON cv.ClassSelection_Link = cs.ClassSelection_Link
  INNER JOIN (
        SELECT 
          c.Log_Link 
        FROM 
          Classes c INNER JOIN 
          ClassValues cv ON c.Class_Link = cv.Class_Link INNER JOIN 
          ClassSelection cs ON cv.ClassSelection_Link = cs.ClassSelection_Link
        WHERE 
          cs.classselection_link = 1
    ) T2 ON c.Log_Link = T2.Log_Link
WHERE 
  cs.classselection_link = 95

SQL内联等效于相交

4 个答案: