mysql - 如何使用mysql查询进行划分

这是我的问题

SELECT currency_code, SUM(
CASE
WHEN TYPE = 'buy'
THEN to_amount
END ) AS BUY, SUM(
CASE
WHEN TYPE = 'sell'
THEN to_amount
END ) AS SELL, SUM(
CASE
WHEN TYPE = 'sell'
THEN rate
END ) AS SELL_RATE, SUM(
CASE
WHEN TYPE = 'buy'
THEN rate
END ) AS BUY_RATE
FROM tb_currency
LEFT JOIN tb_bill ON tb_currency.CURRENCY_ID = tb_bill.CURRENCY_ID
AND tb_bill.TYPE
IN (
'buy', 'sell'
)

输出是
现在我想把BUY字段中的值和BUY_RATE字段中的值分开。我之前尝试了几个查询，得到了错误消息“未知列类型BUY”。
如何解决这个问题？

最佳答案

你需要做一个子选择，像这样

SELECT *, (BUY/BUY_RATE) AS DIV_VALUE FROM (
    SELECT currency_code, SUM(
    CASE
    WHEN TYPE = 'buy'
    THEN to_amount
    END ) AS BUY, SUM(
    CASE
    WHEN TYPE = 'sell'
    THEN to_amount
    END ) AS SELL, SUM(
    CASE
    WHEN TYPE = 'sell'
    THEN rate
    END ) AS SELL_RATE, SUM(
    CASE
    WHEN TYPE = 'buy'
    THEN rate
    END ) AS BUY_RATE
    FROM tb_currency
    LEFT JOIN tb_bill ON tb_currency.CURRENCY_ID = tb_bill.CURRENCY_ID
    AND tb_bill.TYPE
    IN (
    'buy', 'sell'
    )
)

关于mysql - 如何使用mysql查询进行划分，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/4989976/