KQL：连接表后合并 2 列

Question

我想合并我加入 2 个表的 2 个列。这是我的代码：

let Table1 = datatable(ver: string, number:int) 
[
1.0, 5, 
2.0, 5,
2.1, 3 
];
//
let Table2 = datatable(ver: string, number:int) 
[ 
2.0, 3,
2.1, 2,
3.0, 1 
];
//
Table2
| join kind = fullouter Table1 on ver
| extend Delta = number1 - number

这是我得到的：

这就是我需要的：

Answer 1

您可以使用 coalesce() 函数：https://docs.microsoft.com/en-us/azure/data-explorer/kusto/query/coalescefunction

例如：

let Table1 = datatable(ver:string, number:int)
[
    '1.0', 5,
    '2.0', 5,
    '2.1', 3
];
let Table2 = datatable(ver:string, number:int)
[
    '2.0', 3,
    '2.1', 2,
    '3.0', 1
];
Table2
| join kind = fullouter Table1 on ver
| project ver = coalesce(ver, ver1),
          Delta = coalesce(number1, 0) - coalesce(number, 0)

ver	Delta
1.0	5
2.0	2
2.1	1
3.0	-1

KQL：连接表后合并 2 列

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