Mysql 正在创建视图，但获取错误“；视图选择在FROM子句中包含子查询；

这是我正在使用的代码

CREATE VIEW MostBuys AS
SELECT Kundnummer, AntalBest FROM Ordrar
JOIN (SELECT OrderNr, COUNT(*) AS AntalBest
FROM OrderContent
GROUP BY OrderNr) BesAm ON BesAm.OrderNr = Ordrar.OrderNr;

CREATE VIEW MostBuys AS
    SELECT o.Kundnummer,
           (SELECT COUNT(*) AS AntalBest
            FROM OrderContent oc
            WHERE oc.OrderNr = o.OrderNr
           ) as AntalBest
    FROM Ordrar o

我试图计算每个特定整数的OrderNr行数，然后将其与相应的Kundnummer连接起来。这一部分本身起作用

SELECT Kundnummer, AntalBest FROM Ordrar
JOIN (SELECT OrderNr, COUNT(*) AS AntalBest
FROM OrderContent
GROUP BY OrderNr) BesAm ON BesAm.OrderNr = Ordrar.OrderNr;

---

但是我不能用它创建视图。

MySQL不允许在视图的

FROM

子句中使用子查询。啊

您可以将其替换为相关子查询：

这是我正在使用的代码

CREATE VIEW MostBuys AS
SELECT Kundnummer, AntalBest FROM Ordrar
JOIN (SELECT OrderNr, COUNT(*) AS AntalBest
FROM OrderContent
GROUP BY OrderNr) BesAm ON BesAm.OrderNr = Ordrar.OrderNr;

CREATE VIEW MostBuys AS
    SELECT o.Kundnummer,
           (SELECT COUNT(*) AS AntalBest
            FROM OrderContent oc
            WHERE oc.OrderNr = o.OrderNr
           ) as AntalBest
    FROM Ordrar o

---

MySQL不允许在视图的

FROM

子句中进行子查询。啊

您可以将其替换为相关子查询：

这是我正在使用的代码

CREATE VIEW MostBuys AS
SELECT Kundnummer, AntalBest FROM Ordrar
JOIN (SELECT OrderNr, COUNT(*) AS AntalBest
FROM OrderContent
GROUP BY OrderNr) BesAm ON BesAm.OrderNr = Ordrar.OrderNr;

CREATE VIEW MostBuys AS
    SELECT o.Kundnummer,
           (SELECT COUNT(*) AS AntalBest
            FROM OrderContent oc
            WHERE oc.OrderNr = o.OrderNr
           ) as AntalBest
    FROM Ordrar o

---

您可以使用聚合来解决MySQL视图的这一限制：

CREATE VIEW MostBuys AS
SELECT o.Kundnummer, COUNT(oc.OrderNr) AS AntalBest
FROM Ordrar o
LEFT JOIN OrderContent oc ON oc.OrderNr = o.OrderNr
GROUP BY o.Kundnummer

---

您可以使用聚合来解决MySQL视图的这一限制：

CREATE VIEW MostBuys AS
SELECT o.Kundnummer, COUNT(oc.OrderNr) AS AntalBest
FROM Ordrar o
LEFT JOIN OrderContent oc ON oc.OrderNr = o.OrderNr
GROUP BY o.Kundnummer

---

所以问题是我试图在From子句中加入一个子查询？@LinusLiljequist。正如我在回答中所说，问题是MySQL不支持视图中的

FROM

子句中的子查询。因此，问题是我正试图在FROM子句中加入子查询？@LinusLiljequist。正如我在回答中所说，问题在于MySQL不支持视图中

FROM

子句中的子查询。