My application is in Asp.Net coded in C# and i'm using LINQ for database transactions. My requirement is to get the Max value of the records saved in a certain table, for this i'm using Max() method.
Below is my controller code :
[HttpPost]
public ActionResult Create(Entity_Name Entity_Object)
{
if (Entity_Object.Condition == true)
{
My required code
}
else
{
var get_Max_Number = db.Entity_Name.ToList();
long Max_Number = 0;
if (get_Max_Number.Count() > 0)
{
Max_Number = Convert.ToInt64(get_Max_Number.Max());
}
My required code
}
}
My issue is when i remove the If-else condition then the same Max() method query works perfect, but when i add the If-else statement then i gets the following error.
Error:
At least one object must implement IComparable.
What i tried :
I attempted to remove the If-Else
I placed the Max() method logic above the If-else
Placing the Max() method above If-Else
[HttpPost]
public ActionResult Create(Entity_Name Entity_Object)
{
var get_Max_Number = db.Entity_Name.ToList();
long Max_Number = 0;
if (get_Max_Number.Count() > 0)
{
Max_Number = Convert.ToInt64(get_Max_Number.Max());
}
if (Entity_Object.Condition == true)
{
My required code
}
else
{
My required code
}
}
Max() needs to know what you're getting the maximum of. If you're Entity_Name class contains a number of properties (strings, ints etc...) then you need to tell it what to get the Maximum on the basis of.
Another thing, you're connecting to a DB via Linq from the looks of things, but executing your Count() & Max() functions in memory after you've retrieved the entire contents of the database table. This will be very inefficient as the table grows in size. LinqToSql & LinqToEF support pushing those functions down to the database level. I'd recommend changing your code to the following.
[HttpPost]
public ActionResult Create(Entity_Name Entity_Object)
{
if (Entity_Object.Condition == true)
{
//My required code
}
else
{
long Max_Number = 0;
if(db.Entity_Name.Count() > 0)
{
Max_Number = Convert.ToInt64(
db.Entity_Name.Max(x => x.PropertyToGetMaxOf)
);
}
//My required code
}
}
Related
I'm looking for an elegant way to execute a Contains() statement in a scalable way. Please allow me to give some background before I come to the actual question.
The IN statement
In Entity Framework and LINQ to SQL the Contains statement is translated as a SQL IN statement. For instance, from this statement:
var ids = Enumerable.Range(1,10);
var courses = Courses.Where(c => ids.Contains(c.CourseID)).ToList();
Entity Framework will generate
SELECT
[Extent1].[CourseID] AS [CourseID],
[Extent1].[Title] AS [Title],
[Extent1].[Credits] AS [Credits],
[Extent1].[DepartmentID] AS [DepartmentID]
FROM [dbo].[Course] AS [Extent1]
WHERE [Extent1].[CourseID] IN (1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
Unfortunately, the In statement is not scalable. As per MSDN:
Including an extremely large number of values (many thousands) in an IN clause can consume resources and return errors 8623 or 8632
which has to do with running out of resources or exceeding expression limits.
But before these errors occur, the IN statement becomes increasingly slow with growing numbers of items. I can't find documentation about its growth rate, but it performs well up to a few thousands of items, but beyond that it gets dramatically slow. (Based on SQL Server experiences).
Scalable
We can't always avoid this statement. A JOIN with the source data in stead would generally perform much better, but that's only possible when the source data is in the same context. Here I'm dealing with data coming from a client in a disconnected scenario. So I have been looking for a scalable solution. A satisfactory approach turned out to be cutting the operation into chunks:
var courses = ids.ToChunks(1000)
.Select(chunk => Courses.Where(c => chunk.Contains(c.CourseID)))
.SelectMany(x => x).ToList();
(where ToChunks is this little extension method).
This executes the query in chunks of 1000 that all perform well enough. With e.g. 5000 items, 5 queries will run that together are likely to be faster than one query with 5000 items.
But not DRY
But of course I don't want to scatter this construct all over my code. I am looking for an extension method by which any IQueryable<T> can be transformed into a chunky executing statement. Ideally something like this:
var courses = Courses.Where(c => ids.Contains(c.CourseID))
.AsChunky(1000)
.ToList();
But maybe this
var courses = Courses.ChunkyContains(c => c.CourseID, ids, 1000)
.ToList();
I've given the latter solution a first shot:
public static IEnumerable<TEntity> ChunkyContains<TEntity, TContains>(
this IQueryable<TEntity> query,
Expression<Func<TEntity,TContains>> match,
IEnumerable<TContains> containList,
int chunkSize = 500)
{
return containList.ToChunks(chunkSize)
.Select (chunk => query.Where(x => chunk.Contains(match)))
.SelectMany(x => x);
}
Obviously, the part x => chunk.Contains(match) doesn't compile. But I don't know how to manipulate the match expression into a Contains expression.
Maybe someone can help me make this solution work. And of course I'm open to other approaches to make this statement scalable.
I’ve solved this problem with a little different approach a view month ago. Maybe it’s a good solution for you too.
I didn’t want my solution to change the query itself. So a ids.ChunkContains(p.Id) or a special WhereContains method was unfeasible. Also should the solution be able to combine a Contains with another filter as well as using the same collection multiple times.
db.TestEntities.Where(p => (ids.Contains(p.Id) || ids.Contains(p.ParentId)) && p.Name.StartsWith("Test"))
So I tried to encapsulate the logic in a special ToList method that could rewrite the Expression for a specified collection to be queried in chunks.
var ids = Enumerable.Range(1, 11);
var result = db.TestEntities.Where(p => Ids.Contains(p.Id) && p.Name.StartsWith ("Test"))
.ToChunkedList(ids,4);
To rewrite the expression tree I discovered all Contains Method calls from local collections in the query with a view helping classes.
private class ContainsExpression
{
public ContainsExpression(MethodCallExpression methodCall)
{
this.MethodCall = methodCall;
}
public MethodCallExpression MethodCall { get; private set; }
public object GetValue()
{
var parent = MethodCall.Object ?? MethodCall.Arguments.FirstOrDefault();
return Expression.Lambda<Func<object>>(parent).Compile()();
}
public bool IsLocalList()
{
Expression parent = MethodCall.Object ?? MethodCall.Arguments.FirstOrDefault();
while (parent != null) {
if (parent is ConstantExpression)
return true;
var member = parent as MemberExpression;
if (member != null) {
parent = member.Expression;
} else {
parent = null;
}
}
return false;
}
}
private class FindExpressionVisitor<T> : ExpressionVisitor where T : Expression
{
public List<T> FoundItems { get; private set; }
public FindExpressionVisitor()
{
this.FoundItems = new List<T>();
}
public override Expression Visit(Expression node)
{
var found = node as T;
if (found != null) {
this.FoundItems.Add(found);
}
return base.Visit(node);
}
}
public static List<T> ToChunkedList<T, TValue>(this IQueryable<T> query, IEnumerable<TValue> list, int chunkSize)
{
var finder = new FindExpressionVisitor<MethodCallExpression>();
finder.Visit(query.Expression);
var methodCalls = finder.FoundItems.Where(p => p.Method.Name == "Contains").Select(p => new ContainsExpression(p)).Where(p => p.IsLocalList()).ToList();
var localLists = methodCalls.Where(p => p.GetValue() == list).ToList();
If the local collection passed in the ToChunkedList method was found in the query expression, I replace the Contains call to the original list with a new call to a temporary list containing the ids for one batch.
if (localLists.Any()) {
var result = new List<T>();
var valueList = new List<TValue>();
var containsMethod = typeof(Enumerable).GetMethods(BindingFlags.Static | BindingFlags.Public)
.Single(p => p.Name == "Contains" && p.GetParameters().Count() == 2)
.MakeGenericMethod(typeof(TValue));
var queryExpression = query.Expression;
foreach (var item in localLists) {
var parameter = new List<Expression>();
parameter.Add(Expression.Constant(valueList));
if (item.MethodCall.Object == null) {
parameter.AddRange(item.MethodCall.Arguments.Skip(1));
} else {
parameter.AddRange(item.MethodCall.Arguments);
}
var call = Expression.Call(containsMethod, parameter.ToArray());
var replacer = new ExpressionReplacer(item.MethodCall,call);
queryExpression = replacer.Visit(queryExpression);
}
var chunkQuery = query.Provider.CreateQuery<T>(queryExpression);
for (int i = 0; i < Math.Ceiling((decimal)list.Count() / chunkSize); i++) {
valueList.Clear();
valueList.AddRange(list.Skip(i * chunkSize).Take(chunkSize));
result.AddRange(chunkQuery.ToList());
}
return result;
}
// if the collection was not found return query.ToList()
return query.ToList();
Expression Replacer:
private class ExpressionReplacer : ExpressionVisitor {
private Expression find, replace;
public ExpressionReplacer(Expression find, Expression replace)
{
this.find = find;
this.replace = replace;
}
public override Expression Visit(Expression node)
{
if (node == this.find)
return this.replace;
return base.Visit(node);
}
}
Please allow me to provide an alternative to the Chunky approach.
The technique involving Contains in your predicate works well for:
A constant list of values (no volatile).
A small list of values.
Contains will do great if your local data has those two characteristics because these small set of values will be hardcoded in the final SQL query.
The problem begins when your list of values has entropy (non-constant). As of this writing, Entity Framework (Classic and Core) do not try to parameterize these values in any way, this forces SQL Server to generate a query plan every time it sees a new combination of values in your query. This operation is expensive and gets aggravated by the overall complexity of your query (e.g. many tables, a lot of values in the list, etc.).
The Chunky approach still suffers from this SQL Server query plan cache pollution problem, because it does not parametrizes the query, it just moves the cost of creating a big execution plan into smaller ones that are more easy to compute (and discard) by SQL Server, furthermore, every chunk adds an additional round-trip to the database, which increases the time needed to resolve the query.
An Efficient Solution for EF Core
🎉 NEW! QueryableValues EF6 Edition has arrived!
For EF Core keep reading below.
Wouldn't it be nice to have a way of composing local data in your query in a way that's SQL Server friendly? Enter QueryableValues.
I designed this library with these two main goals:
It MUST solve the SQL Server's query plan cache pollution problem ✅
It MUST be fast! ⚡
It has a flexible API that allows you to compose local data provided by an IEnumerable<T> and you get back an IQueryable<T>; just use it as if it were another entity of your DbContext (really), e.g.:
// Sample values.
IEnumerable<int> values = Enumerable.Range(1, 1000);
// Using a Join (query syntax).
var query1 =
from e in dbContext.MyEntities
join v in dbContext.AsQueryableValues(values) on e.Id equals v
select new
{
e.Id,
e.Name
};
// Using Contains (method syntax)
var query2 = dbContext.MyEntities
.Where(e => dbContext.AsQueryableValues(values).Contains(e.Id))
.Select(e => new
{
e.Id,
e.Name
});
You can also compose complex types!
It goes without saying that the provided IEnumerable<T> is only enumerated at the time that your query is materialized (not before), preserving the same behavior of EF Core in this regard.
How Does It Works?
Internally QueryableValues creates a parameterized query and provides your values in a serialized format that is natively understood by SQL Server. This allows your query to be resolved with a single round-trip to the database and avoids creating a new query plan on subsequent executions due to the parameterized nature of it.
Useful Links
Nuget Package
GitHub Repository
Benchmarks
SQL Server Cache Pollution Problem
QueryableValues is distributed under the MIT license
Linqkit to the rescue! Might be a better way that does it directly, but this seems to work fine and makes it pretty clear what's being done. The addition being AsExpandable(), which lets you use the Invoke extension.
using LinqKit;
public static IEnumerable<TEntity> ChunkyContains<TEntity, TContains>(
this IQueryable<TEntity> query,
Expression<Func<TEntity,TContains>> match,
IEnumerable<TContains> containList,
int chunkSize = 500)
{
return containList
.ToChunks(chunkSize)
.Select (chunk => query.AsExpandable()
.Where(x => chunk.Contains(match.Invoke(x))))
.SelectMany(x => x);
}
You might also want to do this:
containsList.Distinct()
.ToChunks(chunkSize)
...or something similar so you don't get duplicate results if something this occurs:
query.ChunkyContains(x => x.Id, new List<int> { 1, 1 }, 1);
Another way would be to build the predicate this way (of course, some parts should be improved, just giving the idea).
public static Expression<Func<TEntity, bool>> ContainsPredicate<TEntity, TContains>(this IEnumerable<TContains> chunk, Expression<Func<TEntity, TContains>> match)
{
return Expression.Lambda<Func<TEntity, bool>>(Expression.Call(
typeof (Enumerable),
"Contains",
new[]
{
typeof (TContains)
},
Expression.Constant(chunk, typeof(IEnumerable<TContains>)), match.Body),
match.Parameters);
}
which you could call in your ChunkContains method
return containList.ToChunks(chunkSize)
.Select(chunk => query.Where(ContainsPredicate(chunk, match)))
.SelectMany(x => x);
Using a stored procedure with a table valued parameter could also work well. You in effect write a joint In the stored procedure between your table / view and the table valued parameter.
https://learn.microsoft.com/en-us/dotnet/framework/data/adonet/sql/table-valued-parameters
I have an object that has a many-to-many relationship with another object. I am trying to write an update statement that doesn't result in having to delete all records from the many-to-many table first.
My data is:
StoredProcedure - StoredProcedureId, Name
Parameter - ParameterId, Name
StoredProcedure_Parameter - StoredProcedureId, ParameterId, Order
I have a UI for updating a stored procedured object (adding/removing parameters or changing the order of the parameters).
When I save, I end up at:
var storedProcedure = context.Sprocs.FirstOrDefault(s => s.SprocID == sproc.StoredProcedureId);
if (storedProcedure == null)
{
//do something like throw an exception
} else
{
storedProcedure.Name = sproc.Name;
//resolve Parameters many to many here
//remove all Params that are not in sproc.Params
//Add any params that are in sproc.Params but not in storedProcedure.Params
//Update the Order number for any that are in both
}
I know I could simply call .Clear() on the table and then reinsert all of the values with their current state (ensuring that all parameters that were removed by the UI are gone, new ones are added, and updated Orders are changed). However, I feel like there must be a better way to do this. Do many-to-many updates with EF usually get resolved by deleting all of the elements and reinserting them?
Here there is my code that I use and it works. The difference is that instead o having your 3 tables( StoredProcedure, StoredProcedure_Parameter and Parameter ) I have the following 3 tables: Order, OrdersItem(this ensure the many-to-many relation) and Item. This is the procedure that I used for updating or add an order, or after I change an existing OrderItem or add a new one to the Order.
public void AddUpdateOrder(Order order)
{
using (var db = new vitalEntities())
{
if (order.OrderId == 0)
{
db.Entry(order).State = EntityState.Added;
}
else
{
foreach (var orderItem in order.OrdersItems)
{
if (orderItem.OrderItemsId == 0)
{
orderItem.Item = null;
if (order.OrderId != 0)
orderItem.OrderId = order.OrderId;
db.Entry(orderItem).State = EntityState.Added;
}
else
{
orderItem.Order = null;
orderItem.Item = null;
db.OrdersItems.Attach(orderItem);
db.Entry(orderItem).State = EntityState.Modified;
}
}
db.Orders.Attach(order);
db.Entry(order).State = EntityState.Modified;
}
SaveChanges(db);
}
}
I have a function inside a class that will run a Linq to Entities query (or any type of Linq query actually), and it's gonna return 2 columns in the resultset. I would like to return an object to whoever is calling my function that will allow Intellisense to know what I have returned.
Let me explain. If I have a function like this:
public static IQueryable GetInfo(MyEntityModel oEntityModel)
{
var query =
(from t in oEntityModel.Table1
from u in t.Table2
where t.Status == true &&
u.Status == true
select new
{
t.Column1,
u.Column2
})
return query;
}
What can (should) I put instead of IQueryable so that whoever calls my GetInfo function, will get Intellisense from the resultset, and show that it has a Column1 and Column2?
var linqresult = ClsLinqTeste.GetInfo(oEntityModel);
if (linqresult.Column1 == 1)
{
foreach (var oItem in linqresult)
{
.. do stuff...
}
}
Tks
You cannot return an anonymous type from a function, they are strictly "inline" classes. When you return it, the foreach loop will only be able to interpret the result as an plain object. I guess you could use reflection to query the property names and values, however it seems much more straight forward to define a data transfer type to hold the results.
See this question, and this blog post.
So you could create a simple struct or class:
public class MyDataResult
{
public object Column1 { get; set; }
public object Column2 { get; set; }
}
Then modify your query in the function:
public static IQueryable<MyDataResult> GetInfo(MyEntityModel oEntityModel)
{
var query =
(from t in oEntityModel.Table1
from u in t.Table2
where t.Status == true &&
u.Status == true
select new MyDataResult
{
Column1 = t.Column1,
Column2 = u.Column2
})
return query;
}
Something like that should work. Note that I used "object" for the properties in MyDataResult. I don't know the types of the columns you are returning, you should use the actual types in order to get full intellisense.
You are returning a collection of anonymous types, they will be casted to objects, so when you try to iterate over them, altough they will be your objects (and they will contain your properties) at compile time they will be casted to objects:
foreach (var x in ClsLinqTeste.GetInfo(oEntityModel))
{
//x is an Object
}
You can read more about it here.
If you want to have intellisense, I suggest you create a custom class they will hold your properties and return not an anonymous type (using new {}) but object of your class (new MyClass(prop1, prop2)). You also need to change signature of your method, so it returns IQueryable<YourClass> and not just plain non-generic IQueryable.
As others have said, creating a new type to hold the two columns is usually the best option.
But if, for some reason, you don't want to do that and you are using .Net 4.0, you can use Tuple:
public static IQueryable<Tuple<Column1Type, Column2Type>>
GetInfo(MyEntityModel oEntityModel)
{
return from …
select Tuple.Create(t.Column1, u.Column2);
}
var linqresult = ClsLinqTeste.GetInfo(oEntityModel);
foreach (var oItem in linqresult)
Console.WriteLIne(oItem.Item1, oItem.Item2);
When you return your resultset AsQueryable, the app is already able to give you intellisense, however in your example, you must specify either .FirstOrDefault if you know your collection will only have a single row, or iterate over your collection to get the items from it, like so:
This is what you're doing:
var linqresult = ClsLinqTeste.GetInfo(oEntityModel);
if (linqresult.Column1 == 1)
{
..do stuff...
}
This is how you should do it:
var linqresult = ClsLinqTeste.GetInfo(oEntityModel);
foreach(var item in linqresult)
{
if (item.Column1 == 1)
{
..do stuff...
}
}
You must iterate over linqresult because when you query with link, it returns a result set, even if it just has one column. As with any collection, your data columns aren't available on the whole result set, only with individual items.
If you want to strongly typed enumerate a non-generic IEnumerable (IEnumerable.GetEnumerator() instead of IEnumerable<T>.GetEnumerator<T>()) you can use the Cast<>() extension, like so
var myquery = GetQueryable();
for (var item in myquery.Cast<MyDataType>())
{
// use item.Column1 directly and strongly typed with intellisense
}
I have a piece of code which combines an in-memory list with some data held in a database. This works just fine in my unit tests (using a mocked Linq2SqlRepository which uses List).
public IRepository<OrderItem> orderItems { get; set; }
private List<OrderHeld> _releasedOrders = null;
private List<OrderHeld> releasedOrders
{
get
{
if (_releasedOrders == null)
{
_releasedOrders = new List<nOrderHeld>();
}
return _releasedOrders;
}
}
.....
public int GetReleasedCount(OrderItem orderItem)
{
int? total =
(
from item in orderItems.All
join releasedOrder in releasedOrders
on item.OrderID equals releasedOrder.OrderID
where item.ProductID == orderItem.ProductID
select new
{
item.Quantity,
}
).Sum(x => (int?)x.Quantity);
return total.HasValue ? total.Value : 0;
}
I am getting an error I don't really understand when I run it against a database.
Exception information:
Exception type: System.NotSupportedException
Exception message: Local sequence cannot be used in LINQ to SQL
implementation of query operators
except the Contains() operator.
What am I doing wrong?
I'm guessing it's to do with the fact that orderItems is on the database and releasedItems is in memory.
EDIT
I have changed my code based on the answers given (thanks all)
public int GetReleasedCount(OrderItem orderItem)
{
var releasedOrderIDs = releasedOrders.Select(x => x.OrderID);
int? total =
(
from item in orderItems.All
where releasedOrderIDs.Contains(item.OrderID)
&& item.ProductID == orderItem.ProductID
select new
{
item.Quantity,
}
).Sum(x => (int?)x.Quantity);
return total.HasValue ? total.Value : 0;
}
I'm guessing it's to do with the fact
that orderItems is on the database
and releasedItems is in memory.
You are correct, you can't join a table to a List using LINQ.
Take a look at this link:
http://flatlinerdoa.spaces.live.com/Blog/cns!17124D03A9A052B0!455.entry
He suggests using the Contains() method but you'll have to play around with it to see if it will work for your needs.
It looks like you need to formulate the db query first, because it can't create the correct SQL representation of the expression tree for objects that are in memory. It might be down to the join, so is it possible to get a value from the in-memory query that can be used as a simple primitive? For example using Contains() as the error suggests.
You unit tests work because your comparing a memory list to a memory list.
For memory list to database, you will either need to use the memoryVariable.Contains(...) or make the db call first and return a list(), so you can compare memory list to memory list as before. The 2nd option would return too much data, so your forced down the Contains() route.
public int GetReleasedCount(OrderItem orderItem)
{
int? total =
(
from item in orderItems.All
where item.ProductID == orderItem.ProductID
&& releasedOrders.Contains(item.OrderID)
select new
{
item.Quantity,
}
).Sum(x => (int?)x.Quantity);
return total.HasValue ? total.Value : 0;
}
I have IQueryable object and I need to take the data inside the IQueryable to put it into Textboxs controls. Is this possible?
I try something like:
public void setdata (IQueryable mydata)
{
textbox1.text = mydata.????
}
Update:
I'm doing this:
public IQueryable getData(String tableName, Hashtable myparams)
{
decimal id = 0;
if (myparams.ContainsKey("id") == true)
id = (decimal)myparams["id"];
Type myType= Type.GetType("ORM_Linq." + tableName + ", ORM_Linq");
return this.GetTable(tableName , "select * from Articu where id_tipo_p = '" + id + "'");
}
public IQueryable<T> GetTable<T>(System.Linq.Expressions.Expression<Func<T, bool>> predicate) where T : class
{
return _datacontext.GetTable<T>().Where(predicate);
}
This returns a {System.Data.Linq.SqlClient.SqlProvider+OneTimeEnumerable1[ORM_Linq.Articu]}`
I don't see any method like you tell me. I see Cast<>, Expression, ToString...
EDIT: Updated based on additional info from your other posts...
Your getData method is returning IQueryable instead of a strongly typed result, which is why you end up casting it. Try changing it to:
public IQueryable<ORM_Linq.Articu> getData(...)
Are you trying to query for "Articu" from different tables?
With the above change in place, your code can be rewritten as follows:
ORM_Linq.Articu result = mydata.SingleOrDefault();
if (result != null)
{
TextBoxCode.Text = result.id.ToString();
TextBoxName.Text = result.descrip;
}
If you have a single result use SingleOrDefault which will return a default value if no results are returned:
var result = mydata.SingleOrDefault();
if (result != null)
{
textbox1.text = result.ProductName; // use the column name
}
else
{
// do something
}
If you have multiple results then loop over them:
foreach (var item in mydata)
{
string name = item.ProductName;
int id = item.ProductId;
// etc..
}
First, you should be using a strongly-typed version of IQueryable. Say that your objects are of type MyObject and that MyObject has a property called Name of type string. Then, first change the parameter mydata to be of type IQueryable<MyObject>:
public void setdata (IQueryable<MyObject> mydata)
Then we can write a body like so to actually get some data out of. Let's say that we just want the first result from the query:
public void setdata (IQueryable<MyObject> mydata) {
MyObject first = mydata.FirstOrDefault();
if(first != null) {
textbox1.Text = first.Name;
}
}
Or, if you want to concatenate all the names:
public void setdata(IQueryable<MyObject> mydata) {
string text = String.Join(", ", mydata.Select(x => x.Name).ToArray());
textbo1.Text = text;
}
Well, as the name suggests, an object implementing IQueryable is... Queryable! You'll need to write a linq query to get at the internal details of your IQueryable object. In your linq query you'll be able to pull out its data and assign bits of it where ever you'd like - like your text box.
Here's a great starting place for learning Linq.
I think you find the same mental struggle when coming from FoxPro and from DataSet. Really nice, powerful string-based capabilities(sql for query, access to tables and columns name) in these worlds are not available, but replaced with a compiled, strongly-typed set of capabilities.
This is very nice if you are statically defining the UI for search and results display against a data source known at compile time. Not so nice if you are trying to build a system which attaches to existing data sources known only at runtime and defined by configuration data.
If you expect only one value just call FirstOrDefault() method.
public void setdata (IQueryable mydata)
{
textbox1.text = mydata.FirstOrDefault().PropertyName;
}