mysql - 具有条件的 SUM 子查询取决于父查询列返回 NULL

Question

大家好!

我正在尝试计算每天的交易价格总和。我做什么:

SET @symbols_set = "A,B,C,D";

DROP TABLE IF EXISTS temp_deals;

CREATE TABLE temp_deals AS SELECT Deal, TimeMsc, Price, VolumeExt, Symbol FROM deals WHERE TimeMsc >= "2019-04-01" AND TimeMsc <= "2019-06-30" AND FIND_IN_SET(Symbol, @symbols_set) > 0;

SELECT
    DATE_FORMAT(TimeMsc, "%d/%m/%Y") AS Date,
    Symbol,
    (SELECT SUM(Price) FROM temp_deals dap WHERE dap.TimeMsc BETWEEN Date AND Date + INTERVAL 1 DAY AND dap.Symbol = Symbol) AS AvgPrice
FROM temp_deals
ORDER BY Date;

DROP TABLE IF EXISTS temp_deals;

但结果我在 AvgPrice 列中得到了 NULL。我不明白我做错了什么。

看起来我不能将父查询的列传递给子查询，对吗？

Answer 1

限定您的列名称。但大多数情况下，不要使用字符串来比较日期:

SELECT DATE_FORMAT(d.TimeMsc, '%d/%m/%Y') AS Date,
       d.Symbol,
       (SELECT SUM(dap.Price)
        FROM temp_deals dap
        WHERE dap.TimeMsc >= d.TimeMsc AND
              dap.TimeMsc < d.TimeMsc + INTERVAL 2 DAY AND  -- not sure if you want 1 day or 2 day
              dap.Symbol = d.Symbol
       ) AS AvgPrice
FROM temp_deals d
ORDER BY d.TimeMsc;