In my code I have a page that includes information from 3 different tables. To show this information I make 3 SQL select calls and unite them in one list to pass as Model to my view. Can I do it with one SQL call? Data has no connection with one another.
My code:
public ActionResult Index()
{
StorePageData PageData = new StorePageData();
return View(PageData);
}
public class StorePageData
{
public List<Table1Data> Table1 { get; set; }
public List<Table2Data> Table2 { get; set; }
public List<Table3Data> Table3 { get; set; }
public StorePageData()
{
Table1 = //loading from Database1
Table2 = //loading from Database2
Table3 = //loading from Database3
}
}
public class Table1Data
{
public int Id { get; set; }
public double Info1 { get; set; }
public string Info2 { get; set; }
}
public class Table2Data
{
public int Id { get; set; }
public List<int> Info1 { get; set; }
public List<int> Info2 { get; set; }
}
public class Table3Data
{
public int Id { get; set; }
public List<string> Info1 { get; set; }
public List<string> Info2 { get; set; }
}
If there is a way to load all 3 tables in one SQL request it will improve significantly the load time of this page.
Thank you.
You can get multiple result sets in a single request using a DataReader
. You can use it with or without entity framework.
If you are using Entity Framework, you can pass a DbDataReader
to ObjectContext.Translate
method to translate multiple result set to requested object types. The command which is used to create the data reader can be a stored procedure, or you can simply use a command containing your queries to shape multiple result set.
Example
List<Table1> list1;
List<Table2> list2;
using (var cn = new SqlConnection(@"Connection String"))
{
cn.Open();
using (var cmd = cn.CreateCommand())
{
cmd.CommandText = "SELECT * FROM Table1; SELECT * FROM Table2";
var reader = cmd.ExecuteReader();
using (var db = new YourDbContext())
{
var context = ((IObjectContextAdapter)db).ObjectContext;
list1 = context.Translate<Table1>(reader).ToList();
reader.NextResult();
list2 = context.Translate<Table2>(reader).ToList();
}
}
}
If you are using SqlDataAdapter
, you can simply pass a command containing your queries and then using Fill
, fill a data set. The data adapter itself will use DataReader
behind the scene.
Example
var connectionString = @"Connection String";
var commandText = "SELECT * FROM Table1; SELECT * FROM Table2;";
var ds = new DataSet();
using (var da = new SqlDataAdapter(commandText, connectionString))
{
da.Fill(ds);
}
Then you can shape the results to List<Table1>
and List<Table2>
.