CODEWITHSUNDEEP
c#sqlentity-framework
MattTheHack
MattTheHack

Reputation: 1384

Entity Framework SQL query not returning results

I am using an Entity Framework Database first model and I am having problems querying my DB.

I'm trying to use the following code: 

var ctx = new dbEntities();
var description = ctx.DEPARTMENTs.SqlQuery("SELECT DESCRIPTION FROM DEPARTMENT WHERE DEPARTMENT='FINANCE'");
System.Diagnostics.Debug.WriteLine(description);

I can see my table of results for the DEPARTMENTs table in the debug log, but for some reason the SQL query is just returning me this in the console rather than executing the query, anybody know why? 

SELECT DESCRIPTION FROM DEPARTMENT WHERE DEPARTMENT='FINANCE'

Upvotes: 6

Views: 11690

Answers (3)

Manish Mishra
Manish Mishra

Reputation: 12375

To make the query execute against the provider, you have to use any extension derived from IEnumerable i.e. ToList() or First() or FirstOrDefault()

Now you have to consider few things. What your query might possibly return? A List of data or a single data? Or even if a list of matches found, you want just the single one?

from the syntax of your query I assume you should be doing this:

var ctx = new dbEntities();
var dep = ctx.DEPARTMENTs
             .SqlQuery("SELECT * FROM DEPARTMENT WHERE DEPARTMENT='FINANCE'")
             .FirstOrDefault();

if(dep!=null)
{
    var description = department.Description;
}

Alternatively, you can also do this(I would prefer):

var description = ctx.DEPARTMENTs.Where(s=>s.Department.ToUpper() =="FINANCE")
                     .Select(s=>s.Description)
                     .FirstOrDefault();

Upvotes: 8

Mihai Hantea
Mihai Hantea

Reputation: 1743

Try:

var description = ctx.DEPARTMENTs.SqlQuery<string>("SELECT DESCRIPTION FROM DEPARTMENT WHERE DEPARTMENT='FINANCE'").ToList();

EDIT: Raw SQL Queries http://msdn.microsoft.com/en-us/data/jj592907.aspx

Note that, just as for LINQ queries, the query is not executed until the results are enumerated—in the example above this is done with the call to ToList.

System.Diagnostics.Debug.WriteLine(Object) writes the value of the object's ToString method to the trace listeners in the Listeners collection. Debug.WriteLine(Object)

Upvotes: 4

Hossain Muctadir
Hossain Muctadir

Reputation: 3626

SqlQuery returns DbSqlQuery<TEntity> object. In your case it is probably DbSqlQuery<DEPARTMENTs>. As the documentation says

Represents a SQL query for entities that is created from a System.Data.Entity.DbContext and is executed using the connection from that context. Instances of this class are obtained from the System.Data.Entity.DbSet instance for the entity type. The query is not executed when this object is created; it is executed each time it is enumerated, for example by using foreach. SQL queries for non-entities are created using the System.Data.Entity.DbContext.Database. See System.Data.Entity.Infrastructure.DbSqlQuery for a non-generic version of this class.

Please note the lines

The query is not executed when this object is created; it is executed each time it is enumerated, for example by using foreach.

Which means you have to iterate it to get the results.

Upvotes: 1

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