Question

WITH vTable1 AS (
SELECT PartNumber
FROM Inventory
WHERE Quantity > 1 
)

SELECT 
    [A whole bunch of conditions for tags] +
    CASE WHEN vTable1.PartNumber IS NOT NULL THEN 'yes' ELSE 'no' END AS 'TagValue'
FROM Inventory
LEFT JOIN vTable1 ON Inventory.PartNumber = vTable1.PartNumber

所以这是我试图做的一个非常一般的例子，所以请耐心等待。

这个想法在我的CTE中，我有一组条件返回PartNumbers列表。我只想在返回给我的PartNumber超过10个时才添加标记值。否则，请留空。

我设置的当前方式加入vTable1而不考虑行数。

如果CTE超过10行，我将如何仅添加标记值？

由于

Answer 1

使用if / then logic

If [your condition]
begin

SELECT 
    [A whole bunch of conditions for tags] +
    [ADD TAG]'TagValue'
FROM Inventory
LEFT JOIN vTable1 ON Inventory.PartNumber = vTable1.PartNumber

end


else
begin 

SELECT 
    [A whole bunch of conditions for tags] +
   [no tag added]
FROM Inventory
LEFT JOIN vTable1 ON Inventory.PartNumber = vTable1.PartNumber


end

Answer 2

解决方案是在子查询中使用计数：

WITH vTable1 AS (
    SELECT PartNumber
    FROM Inventory
    WHERE Quantity > 1 
)
SELECT 
    [A whole bunch of conditions for tags] +
    CASE WHEN (SELECT COUNT(1) FROM vTable1 AS X) >= 10 THEN 'yes' ELSE 'no' END AS 'TagValue'
FROM Inventory
LEFT JOIN vTable1 ON Inventory.PartNumber = vTable1.PartNumber

另一个是在CTE中使用窗口COUNT()。

WITH vTable1 AS (
    SELECT PartNumber, TotalParts = COUNT(1) OVER()
    FROM Inventory
    WHERE Quantity > 1 
)
SELECT 
    [A whole bunch of conditions for tags] +
    CASE WHEN vTable1.TotalParts >= 10 THEN 'yes' ELSE 'no' END AS 'TagValue'
FROM Inventory
LEFT JOIN vTable1 ON Inventory.PartNumber = vTable1.PartNumber

根据行数加入CTE

2 个答案: