据我所知我是这么做的，

create table #temp([index] int identity(0,1),DateTime datetime,Biomass int,Fossil int,Brown int,[coal/Lignite] int
,[Fossil_Coal-derived] int,gas int)

select * from #temp

insert into #temp(DateTime,Biomass,Fossil,Brown,[coal/Lignite],[Fossil_Coal-derived],gas)
values('2/3/2018 23:30',4801,17356,589,1246,5200,192)

select SUM([Biomass]+[Fossil]+[Brown]+[coal/Lignite]+[Fossil_Coal-derived]+[gas]) total
From #temp
Where [index] = '0'
Group by DateTime

我想这就是你想要达到的目标：

SELECT [DateTime],
    SUM(Biomass + 
    [Fossil Brown coal/Lignite] + 
    [Fossil Coal-derived gas]) AS MySum
FROM test
WHERE Index = 0
GROUP BY [DateTime]

仅供参考-您可能需要考虑将某些列重命名为不会像这样过度使用特殊字符的列。
编辑（对于mysql）：

SELECT `DateTime`,
    SUM(Biomass + 
    `Fossil Brown coal/Lignite` + 
    `Fossil Coal-derived gas`) AS MySum
FROM test
WHERE Index = 0
GROUP BY `DateTime`

你似乎想要：

SELECT [DateTime], SUM(Biomass + [Fossil Brown coal/Lignite] + [Fossil Coal-derived gas])
FROM test t
WHERE ID = '0'
GROUP BY [DateTime];

编辑：您的错误提示 MySQL ，因此您的查询将是

SELECT `DateTime`, SUM(`Biomass` + `Fossil Brown coal/Lignite` + `Fossil Coal-derived gas`)
FROM `test` t
WHERE `ID` = '0'
GROUP BY `DateTime`;

当需要对行（而不是列）求和时，可以使用sum（）。
要对字段求和，只需使用运算符。
请尝试以下代码： SELECT ( Biomass + Fossil + Brown + Coal ) AS result FROM test WHERE ID = '0';