Question

我将举例说明我所拥有的桌子

Supplier | Value
sup1     |   4
sup2     |   1
sup1     |   0
sup1     |   3
sup2     |   5

我需要一个可以按供应商求平均值的结果，但是如果供应商的值为0，请不要求平均值，而应返回0

它应该像这样：

Supplier | Value
sup1     |   0
sup2     |   3

Answer 1

这是一个小技巧，但它应该可以工作：

SELECT  Supplier,
        CASE WHEN MIN(ABS(Value)) = 0 THEN 0 ELSE AVG(Value) END 
FROM    TableTest
GROUP BY Supplier

编辑：使用ABS（）函数可以避免出现负值问题

Answer 2

DECLARE @TAB TABLE (SUPPLIER VARCHAR(50),VALUE INTEGER)

INSERT INTO @TAB
SELECT 'sup1',4
UNION ALL
SELECT 'sup2',1
UNION ALL
SELECT 'sup1',0
UNION ALL
SELECT 'sup1',3
UNION ALL
SELECT 'sup2',5

SELECT * FROM @TAB

SELECT T1.SUPPLIER,CASE WHEN EXISTS(SELECT 1 FROM @TAB T WHERE T.SUPPLIER = T1.SUPPLIER AND T.VALUE = 0) THEN 0 ELSE AVG(T1.VALUE) END  AS VALUE
FROM @TAB T1
GROUP BY T1.SUPPLIER

结果

SUPPLIER    VALUE
sup1        0
sup2        3

Answer 3

使用以下查询是一种方法。

首先，我推入Value = 0的供应商，然后根据结果，我将执行剩余的计算，最后使用UNION获得预期结果：

DECLARE @ZeroValue TABLE (Supplier VARCHAR (20));

INSERT INTO @ZeroValue (Supplier)
SELECT Supplier FROM TestTable WHERE Value = 0

SELECT Supplier, 0 AS Value FROM @ZeroValue
UNION
SELECT T.Supplier, AVG(T.Value) AS Value
FROM TestTable T
JOIN @ZeroValue Z ON Z.Supplier != T.Supplier
GROUP BY T.Supplier

用于示例的模式：

CREATE TABLE TestTable (Supplier VARCHAR (20), Value INT);

INSERT INTO TestTable (Supplier, Value) VALUES
('sup1', 4), ('sup2', 1), ('sup1', 0), ('sup1', 3), ('sup2', 5);

请找到working demo on db<>fiddle

如果只有一个零值，则按供应商分组并显示零；如果没有零，则平均所有值

3 个答案: