是給定的查詢在sql中是否有效？

Question

SELECT account_name ,SUM(debit)+SUM(credit) AS 'total_balance' 
AND SUM(total_balance) AS 'net_revenue' 
FROM transaction 

我想找到總餘額和總餘額爲淨營收的sum及其給我下面的SQL錯誤

#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'and sum(total_balance) as 'net_revenue' from transaction' at line 2 

Answer 1

只需刪除AND即可。

SELECT 
    account_name, 
    SUM(debit)+SUM(credit) AS 'total_balance', 
    SUM(total_balance) AS 'net_revenue' 
FROM transaction 

注：雖然上面的查詢語法有效，SUM是一組功能，你可能會需要一些GROUP BY子句來正確選擇account_name。事情是這樣的：

SELECT 
    account_name, 
    SUM(debit)+SUM(credit) AS 'total_balance', 
    SUM(total_balance) AS 'net_revenue' 
FROM transaction 
GROUP BY account_name 

Answer 2

不，這不是有效的SQL。使用逗號分隔選擇列表中的列。

SELECT account_name ,SUM(debit)+SUM(credit) AS 'total_balance', 
    SUM(total_balance) AS 'net_revenue' 
FROM transaction 

列表像apples, bananas and plums形成是自然英語常見，但不是在代碼。

Answer 3

兩件事錯在這裏：

1. AND是一個布爾運算符。您需要使用逗號分隔多個列
2. 您需要按帳戶名稱進行分組，以按帳戶名稱獲取計算值。

因此改變你的查詢：

SELECT account_name, SUM(debit)+SUM(credit) AS 'total_balance', SUM(total_balance) AS 'net_revenue' 
FROM transaction 
GROUP BY account_name