从mysql中的别名获取总和

Question

This is my sql code

SELECT qty, unitprice, qty * unitprice as Stock FROM item

Form this i want to get the SUM of Stock

Answer 1

It is not clear what you are asking here. I'm not sure about the ultimate goal you are trying to achieve, but this will bring you SUM of all qty * unitprice :

SELECT qty, unitprice, SUM(qty * unitprice) as Stock FROM item

And this is literally bring you SUM of Stock :

SELECT SUM(Stock) as SUM_OF_STOCK
FROM 
    (SELECT qty, unitprice, qty * unitprice as Stock 
     FROM item)

If none of above query fit your needs, I think you really need to edit the question and elaborate more on what you are trying achieve.