sql - 插入零值行

Question

我有以下结构。我想要实现的是，如果由于某种原因其中一个类别不存在，那么与其没有该类别的行，不如应该有一个 x/y/z 为零的行。

以下内容似乎有点令人费解-实现此目的的正确方法是什么？

TRUNCATE TABLE dbo.xxx;
INSERT INTO dbo.xxx
    values
    ('cat_1',0.0,0.0,0.0),
    ('cat_2',0.0,0.0,0.0),
    ('cat_3',0.0,0.0,0.0),
    ('cat_4',0.0,0.0,0.0);


--:: category 1
INSERT INTO dbo.xxx
SELECT  Category = 'cat_1',
        x       = SUM(x),
        y       = SUM(y),
        z       = SUM(z)    
FROM    dbo.yyy x
WHERE   DateKey >= period1;

--:: category 2
INSERT INTO dbo.xxx
SELECT  Category = 'cat_2',
        x       = SUM(x),
        y       = SUM(y),
        z       = SUM(z)    
FROM    dbo.yyy x
WHERE   DateKey >= period2;

--:: category 3
INSERT INTO dbo.xxx
SELECT  Category = 'cat_3',
        x       = SUM(x),
        y       = SUM(y),
        z       = SUM(z)    
FROM    dbo.yyy x
WHERE   DateKey >= period3;

--:: category 4
INSERT INTO dbo.xxx
SELECT  Category = 'cat_4',
        x       = SUM(x),
        y       = SUM(y),
        z       = SUM(z)    
FROM        dbo.yyy x
WHERE   DateKey >= period4;

SELECT  Category,
        x       = SUM(x),
        y       = SUM(y),
        z       = SUM(z)
INTO    #temp
FROM    dbo.xxx
GROUP BY Category;

TRUNCATE TABLE dbo.xxx;

INSERT INTO dbo.xxx
SELECT * FROM #temp;

Answer 1

您可以使用COALESCE或NVL定义替代方案NULL

--:: category 1
INSERT INTO dbo.xxx
SELECT  Category = 'cat_1',
        x       = COALESCE (SUM(x),0),
        y       = COALESCE (SUM(y),0),
        z       = COALESCE (SUM(z),0)    
FROM    dbo.yyy x
WHERE   DateKey >= period1;