Unable to translate set operation when matching columns on both sides have different store types

权达罗 1

(
from item in _context.Table1
select new SomeModel
{
Name ="A"
}
)
.Union
(
from item in _context.Table2
select new SomeModel
{
Name = Convert.ToString(item.UserName)
}
)
it is not work,and throw out：Unable to translate set operation when matching columns on both sides have different store types.
Why?

Jack J Jun 24,296 Reputation points Microsoft Vendor

2022-07-07T07:41:30.417+00:00

@权达罗 , Welcome to Microsoft Q&A, based on my test, I could not reproduce your problem even if I used the same code with you. However, I find the simliar issue in the stack overflow. You could add .AsEnumerable() for the first query before .Union may fix the issue.

Link:Can't process set operations after client evaluation efcore

1 answer

Bruce (SqlWork.com) 56,686 Reputation points

2022-07-05T01:32:03.443+00:00

the linq expression must be converted to sql. The Convert function is not supported. if using a late enough version .ToString() should work:

Name = item.UserName.ToString()
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权达罗 1 Reputation point

2022-07-05T02:43:07.847+00:00

version : .net 6+Microsoft.EntityFrameworkCore 6.0.6

i try ToString(),but ,not work:

var qry1 = from a in UnitWork.Find<Table1>(null) select new { Name = "q", Id = a.Id, }; var qry2 = from b in UnitWork.Find<Table2>(null) select new { Name=b.Name.ToString(), Id=b.Id }; var list = qry1.Union(qry2).ToList();

throw:Unable to translate set operation after client projection has been applied. Consider moving the set operation before the last 'Select' call.
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