Question
I'm executing this simple query with Entity Framework
db.Database.SqlQuery<string>("SELECT * FROM hospital");
But I got this error:
The data reader has more than one field. Multiple fields are not valid for EDM primitive or enumeration types.
What could be the problem?
Accepted Answer
It would be useful to see what the hospital table looks like but assuming something simple like hospital consists of HospitalId and HospitalName then you have a couple of choices.
db.Database.SqlQuery<IEnumerable<string>>("SELECT hospitalName FROM hospital"); //would work if all you're trying to do is get the Name
db.Database.SqlQuery<MyEntity>("SELECT * FROM hospital"); //where you define MyEntity as the same structure as the table would work
db.Database.SqlQuery<IEnumerable<Tuple<int, string>>>("SELECT * FROM hospital"); // would theoretically work although I haven't tried it. Where the Tuple items would have to match the database types in order. I.e. if field 1 is an int and field 2 is a string then Tuple<int,string>
Basically the error is the code doesn't know how to stuff the structure of hospital into a string
Popular Answer
You might also get this error if you are trying to execute an INSERT, UPATE or DELETE command
Instead of using SqlQuery use ExecuteSqlCommand
using (var ctx = new SchoolDBEntities())
{
int noOfRowUpdated = ctx.Database.ExecuteSqlCommand("Update student
set studentname ='changed student by command' where studentid=1");
int noOfRowInserted = ctx.Database.ExecuteSqlCommand("insert into student(studentname)
values('New Student')");
int noOfRowDeleted = ctx.Database.ExecuteSqlCommand("delete from student
where studentid=1");
}
For more details visit - http://www.entityframeworktutorial.net/EntityFramework4.3/raw-sql-query-in-entity-framework.aspx
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