重寫avg而不帶子查詢

Question

如何在沒有子查詢的情況下重寫此查詢？

select i.invoice_number, i.invoice_total 
    from invoices i 
where i.invoice_total>(select avg(payment_total) 
          from invoices); 

Answer 1

爲you..using只有一個選擇萬兆+，無笛卡爾自變體加入:)

SQL> select avg(payment_total) 
    2 from invoices; 

AVG(PAYMENT_TOTAL) 
------------------ 
       5.4 

SQL> select invoice_number, invoice_total, payment_total 
    2 from invoices 
    3 model return updated rows 
    4 dimension by (row_number() over (order by 1) rn, 
    5    case when invoice_total > avg(payment_total) over() then 1 else 2 end a) 
    6 measures (invoice_total, invoice_number, payment_total) 
    7 rules (
    8  invoice_number[any, 1] = invoice_number[cv(rn), 1] 
    9 ) 
10 order by 1; 

INVOICE_NUMBER INVOICE_TOTAL PAYMENT_TOTAL 
-------------- ------------- ------------- 
      6    6    1 
      7    7    8 
      8    8    4 
      9    9    7 
      10   10    6 

「返回更新行「..我們只返回我們觸摸的行。我們將每行標記爲case when invoice_total > avg(payment_total) over() then 1 else 2 end a是否超出平均值。即那些平均超過a的行設爲1。那麼我們只需1invoice_number[any, 1] = invoice_number[cv(rn), 1]（即不要更改任何數據......只是將其更新爲自己）癢癢行。

比原始查詢：？？

SQL> select i.invoice_number, i.invoice_total , i.payment_total 
    2 from invoices i 
    3 where i.invoice_total>(select avg(payment_total) 
    4       from invoices) 
    5 order by 1; 

INVOICE_NUMBER INVOICE_TOTAL PAYMENT_TOTAL 
-------------- ------------- ------------- 
      6    6    1 
      7    7    8 
      8    8    4 
      9    9    7 
      10   10    6 

Answer 2

select 
    invoice_number, 
    invoice_total 
from (
    select 
    invoice_number, 
    invoice_total , 
    avg(payment_total) over() avg_payment_total 
    from 
    invoices) 
where 
    invoice_total>avg_payment_total; 

Answer 3

這裏有幾種方法可以做到這一點。我不保證你的教授會接受他們。

對於我們的第一選擇，首先要創建一個功能：

CREATE OR REPLACE FUNCTION AVG_PAYMENT_TOTAL_FUNC RETURN NUMBER IS 
    nAvg_payment_total NUMBER; 
BEGIN 
    SELECT AVG(PAYMENT_TOTAL) 
    INTO nAvg_payment_total 
    FROM INVOICES; 

    RETURN nAvg_payment_total; 
END AVG_PAYMENT_TOTAL_FUNC; 

，那麼你使用該功能在查詢：

select i.invoice_number, i.invoice_total 
    from invoices i 
    where i.invoice_total > AVG_PAYMENT_TOTAL_FUNC; 

第二種方案是創建一個視圖：

CREATE OR REPLACE VIEW AVG_PAYMENT_TOTAL_VIEW AS 
    SELECT AVG(PAYMENT_TOTAL) AS AVG_PAYMENT_TOTAL 
    FROM INVOICES; 

然後您的查詢變成

SELECT i.INVOICE_NUMBER, 
     i.INVOICE_TOTAL, 
     t.AVG_PAYMENT_TOTAL 
    FROM INVOICES i 
    CROSS JOIN AVG_PAYMENT_TOTAL_VIEW t; 

缺少這樣的東西我看不到一種方法來完成你已經分配的東西。更重要的是，我無法想象任何理由爲什麼有人會在乎查詢中是否有一個或兩個SELECT關鍵字。要求開發人員想出一些古怪/怪異/書呆子的方式來完成上述所有內容，只需一個SELECT關鍵字就可以完成上述操作，這是浪費時間。有完全合理的方法可以快速而合理地完成這項工作;要求某人解決問題否則既不生產也不高效，因此是IMO的無意義。

分享和享受。

Answer 4

with average as (select avg(payment_total) avgtot 
       from invoices) 
select i.invoice_number, i.invoice_total 
    from invoices i 
    , average a 
where i.invoice_total>a.avgtot; 

Answer 5

只有一個SELECT :-)

select i1.invoice_number, i1.invoice_total 
from invoices i1, invoices i2 
group by i1.invoice_number, i1.invoice_total 
having i1.invoice_total > avg(i2.payment_total)