Question

我有这个用于计算组件的SQL查询：

SELECT COUNT(CS.COMPONENTTYPEID) AS CNT
FROM COMPONENTTYPE CT LEFT
OUTER JOIN COMPONENTSTATS CS ON CS.COMPONENTTYPEID = CT.COMPONENTTYPEID
WHERE CT.COMPONENTTYPEID IN (?, ?)
GROUP BY CT.NAME,
         CT.COMPONENTTYPEID
ORDER BY CT.COMPONENTTYPEID

我想选择所有status = 'Active'的组件。我必须插入的正确位置在哪里？也许这个：

SELECT COUNT(CS.COMPONENTTYPEID) AS CNT
FROM COMPONENTTYPE CT LEFT
OUTER JOIN COMPONENTSTATS CS ON CS.COMPONENTTYPEID = CT.COMPONENTTYPEID
WHERE CT.COMPONENTTYPEID IN (?, ?) WHERE STATUS = 'Active'
GROUP BY CT.NAME,
         CT.COMPONENTTYPEID
ORDER BY CT.COMPONENTTYPEID

Answer 1

SELECT COUNT(CS.COMPONENTTYPEID) AS CNT
FROM COMPONENTTYPE CT 
    LEFT OUTER JOIN COMPONENTSTATS CS ON CS.COMPONENTTYPEID = CT.COMPONENTTYPEID AND CS.STATUS = 'Active'
WHERE CT.COMPONENTTYPEID IN (?, ?) 
GROUP BY CT.NAME, CT.COMPONENTTYPEID
ORDER BY CT.COMPONENTTYPEID

过滤器应该在join子句上，因为它用于创建连接表的结果集。

Answer 2

你要么需要一个复合词，否则你就无法使用左连接..

SELECT COUNT(CS.COMPONENTTYPEID) AS CNT
FROM COMPONENTTYPE CT 
LEFT OUTER JOIN COMPONENTSTATS CS 
  ON CS.COMPONENTTYPEID = CT.COMPONENTTYPEID
WHERE CT.COMPONENTTYPEID IN (?, ?) and (STATUS = 'Active' or Status is null)
GROUP BY CT.NAME,
         CT.COMPONENTTYPEID
ORDER BY CT.COMPONENTTYPEID

或者你必须在限制条件上加上限制标准。

SELECT COUNT(CS.COMPONENTTYPEID) AS CNT
FROM COMPONENTTYPE CT 
LEFT OUTER JOIN COMPONENTSTATS CS 
  ON CS.COMPONENTTYPEID = CT.COMPONENTTYPEID
  AND (STATUS = 'Active')
WHERE CT.COMPONENTTYPEID IN (?, ?) 
GROUP BY CT.NAME,
         CT.COMPONENTTYPEID
ORDER BY CT.COMPONENTTYPEID

Answer 3

由于STATUS列位于COMPONENTSTATS表中，因此查询应为

SELECT COUNT(CS.COMPONENTTYPEID) AS CNT
FROM COMPONENTTYPE CT LEFT
OUTER JOIN COMPONENTSTATS CS ON CS.COMPONENTTYPEID = CT.COMPONENTTYPEID
WHERE CT.COMPONENTTYPEID IN (?, ?) AND CS.STATUS = 'Active'
GROUP BY CT.NAME,
         CT.COMPONENTTYPEID
ORDER BY CT.COMPONENTTYPEID

根据状态选择

3 个答案: