使用函數SUM？

Question

我有這個疑問：

Select t1.col5, 
 
     t1.col6, 
 
     SUM(CASE WHEN t2.col1 = 'A' THEN t2.col2 ELSE 0 
 
       WHEN t2.col1 = 'B' THEN t2.col2 * -1 ELSE 0 
 
     END) AS price, 
 
     SUM(CASE WHEN t2.col1 = 'C' THEN t2.col2 + 100 ELSE 0 
 
     END) AS bonus 
 
     FROM t1, t2 
 
     WHERE t1.col1 = t2.col4 
 
     AND (price + bonus) <> 0 
 
     GROUP BY t1.col5, 
 
       t1.col6

，但我不能這樣做（價格+獎金）<> 0？我有這個消息：價格無效的標識符！ 我怎麼能在WHERE中使用我的SUM的名字？ 謝謝:)

Answer 1

不能使用列別名（或者，就此而言，彙總s）在WHERE條款中。所以你想要做的就是使用子查詢，或者把聚合放在HAVING子句中。我會告訴下面的子查詢，我認爲這是容易，因爲你沒有重現所有按鍵（你需要使用的聚集本身，而不是他們的別名，在HAVING條款）：

SELECT * FROM (
    Select t1.col5, 
      t1.col6, 
      SUM(CASE WHEN t2.col1 = 'A' THEN t2.col2 ELSE 0 
       WHEN t2.col1 = 'B' THEN t2.col2 * -1 ELSE 0 
      END) AS price, 
      SUM(CASE WHEN t2.col1 = 'C' THEN t2.col2 + 100 ELSE 0 
      END) AS bonus 
     FROM t1, t2 
     WHERE t1.col1 = t2.col4 
     GROUP BY t1.col5, 
      t1.col6 
) WHERE (price + bonus) <> 0 

Answer 2

您不能使用別名 - 檢查出的操作順序在一個SQL查詢：http://www.bennadel.com/blog/70-sql-query-order-of-operations.htm

你需要嘗試是這樣的：

Select t1.col5, 
     t1.col6, 
     SUM(CASE WHEN t2.col1 = 'A' THEN t2.col2 ELSE 0 
       WHEN t2.col1 = 'B' THEN t2.col2 * -1 ELSE 0 
     END) AS price, 
     SUM(CASE WHEN t2.col1 = 'C' THEN t2.col2 + 100 ELSE 0 
     END) AS bonus 
     FROM t1, t2 
     WHERE t1.col1 = t2.col4 
     AND (SUM(CASE WHEN t2.col1 = 'A' THEN t2.col2 ELSE 0 WHEN t2.col1 = 'B' THEN t2.col2 * -1 ELSE 0 END) 
      + 
      SUM(CASE WHEN t2.col1 = 'C' THEN t2.col2 + 100 ELSE 0 END)) <> 0 
      GROUP BY t1.col5, 
        t1.col6 

Answer 3

上約束聚合函數需要在HAVING子句來完成：

Select t1.col5, 
     t1.col6, 
     SUM(CASE WHEN t2.col1 = 'A' THEN t2.col2 ELSE 0 
       WHEN t2.col1 = 'B' THEN t2.col2 * -1 ELSE 0 
     END) AS price, 
     SUM(CASE WHEN t2.col1 = 'C' THEN t2.col2 + 100 ELSE 0 
     END) AS bonus 
     FROM t1, t2 
     WHERE t1.col1 = t2.col4 

     GROUP BY t1.col5, 
       t1.col6 
    having SUM(CASE WHEN t2.col1 = 'A' THEN t2.col2 ELSE 0 
       WHEN t2.col1 = 'B' THEN t2.col2 * -1 ELSE 0 
     END) + SUM(CASE WHEN t2.col1 = 'C' THEN t2.col2 + 100 ELSE 0 
     END) <> 0