union of different types using linq2db

Question

I have type definition of DocumentField_1 & DocumentField_2, which is totally different.

DocumentField_1 has records if assigned value is true otherwise record will not be there, so it is of boolean type. and DocumentField_2 has value with date.

I have following query in sql which I want to write using linq2db.

What is the way to do that having said that those are of different types (boolean & date)?

select 'True' from DocumentField_1 where DocumentField_1.DocumentId = 2
union all
select CONVERT(varchar, value) from DocumentField_2 where DocumentField_2.DocumentId = 2

schema of DocumentField_1 is

Id          -> int
DocumentId  -> int

schema of DocumentField_2 is

Id          -> int
DocumentId  -> int
Value       -> datetime

I wonder what is your dbms that doesn't throw on `select .., (select .. union select ..) as value ..` every time when inner selects return distinct values? — Serg, Sep 02 '19 at 18:29

score 4 · Accepted Answer · answered Sep 03 '19 at 09:06

If I understand your question correctly, it should be simple:

subquery1.Select(_ => “True”).UnionAll(subquery2.Select(_ => _.Date.ToString());

Instead of ToString(), you can also use Sql.Convert / Sql.Convert2 extensions to customize format

union of different types using linq2db

1 Answers1