[المتألق9]

السلام عليكم
Select price-Q ,(price-Q)*Qw , (price-Q)*Qe from items
هل يوجد طريقة لعدم تكرار )price -Q

[sanyor77]

نعم، يمكن تعريف متغير للحفاظ على قيمة (price - Q) وتطبيقه في الصيغ الأخرى. بعض الأمثلة: 

MySQL:

كود :

SELECT price, (@diff := price - Q) AS diff, @diff * Qw, @diff * Qe
FROM items;

PostgreSQL:

كود :

WITH cte AS (
 SELECT price, (price - Q) AS diff
 FROM items
)
SELECT price, diff, diff * Qw, diff * Qe
FROM cte;

Microsoft SQL Server:

كود :

WITH cte AS (
 SELECT price, (price - Q) AS diff
 FROM items
)
SELECT price, diff, diff * Qw, diff * Qe
FROM cte;

SQLite:

كود :

WITH cte AS (
 SELECT price, (price - Q) AS diff
 FROM items
)
SELECT price, diff, diff * Qw, diff * Qe
FROM cte;