Question

您好，只是学习SQL Server

这给了我一个错误：

 Incorrect syntax near ')'.'

查询：

SELECT p1.categoryid
    ,p1.productname
    ,p1.unitprice
FROM production.products AS p1
CROSS APPLY (
    SELECT min(p2.unitprice)
    FROM production.products AS p2
    WHERE p1.categoryid = p2.categoryid
    )

Answer 1

您仍需要表别名并定义列：

select p1.categoryid, p1.productname, p1.unitprice
from production.products p1 cross apply
     (select min(p2.unitprice) as minunitprice
      from production.products p2
      where p1.categoryid = p2.categoryid
     ) p2;

您没有从子查询中选择任何内容。我假设你打算：

select p1.categoryid, p1.productname, p1.unitprice, p2.minunitprice
from production.products p1 cross apply
     (select min(p2.unitprice) as minunitprice
      from production.products p2
      where p1.categoryid = p2.categoryid
     ) p2;

如果是这样，您可以将其写为：

select p.*, min(p.unitprice) over (partition by p.categoryid)
from production.products p;

Answer 2

交叉应用块之后，您应该添加别名。

SELECT p1.categoryid
    ,p1.productname
    ,p1.unitprice
    ,X.min_unitPrice
FROM products AS p1
CROSS APPLY (
    SELECT min(unitprice) min_unitPrice
    FROM products  p2
    WHERE p1.categoryid = p2.categoryid
    ) X

Answer 3

您需要为子查询列指定别名，如下所示：

min(p2.unitprice) unitprice

交叉应用子查询

3 个答案: