Union Query Result Set

Question

Hi,

I have a requirement like below mentioned.

Query1:

let Source = 'A'
TableA|where SourceType=Source |project ColumnA,ColumnB;
TableB|where SourceType=Source |project ColumnA,ColumnB,ColumnC;
union TableA,TableB

when i change the input parameter i.e. Source='A' then i could fetch the columns from TableA (there won't be any data in SourceType='A' in the TableB)
when i change the input parameter i.e. Source='B' then i could fetch the columns from TableB(there won't be any data in SourceType='B' in the TableA)

how could i do it in the above scenario without writing two separate queries. Because the number of output columns vary from source to source.

Please help on this.

Thanks,
Kesav

Answer 1

Hi @ADX ,

Thank you for posting query in Microsoft Q&A Platform.

You can consider taking result sets of tableA and tableB in to temporary result sets using let keyword and then finally perform union on these results.

Please check below sample implementation. Here tableA and 'tableB` are temporary in memory tables.

Hope this helps. Please let us know if any further queries.

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