LINQ basic query samples in csharp asp.net with join

Assuming “db” is considered as databasecontext object

/////// typical query with condition that returns annonymous object ///////////
var contacts =
from customer in db.Customers
where customer.Name.StartsWith(“A”) && customer.Orders.Count > 0
orderby customer.Name
select new { customer.Name, customer.Phone };

/////// get count with running query///////////
var query = (from o in Order
where CustomerID = 2
select o).Count();

/////////////// inner join (matching in both only) //////////////

var cr = from c in MyDatabase.GetReadOnlyContext().tblCategories
join p in MyDatabase.GetReadOnlyContext().tblProducts on c.CategoryId equals p.CategoryId
select new { c.CategoryName, p.ProductName };

//////////////// left outer joing

var crForLeftOuterJoin = from cat in dc.tblCategories
join pro in dc.tblProducts
on cat.CategoryId equals pro.CategoryId
into xname
from pro in xname.DefaultIfEmpty()
select new {
CAP_Cat = cat.CategoryName,
CAP_Product = pro == default(tblProduct) ? “(no product)” : pro.ProductName
};

//////// getting rows from table as LIST collection /////////////
List lstCat= dc.tblCategories.ToList();

//////// getting rows from table as Array /////////////
tblCategory[] arrCat= dc.tblCategories.ToArray();

///////////////seeking particular element/single element from query ///////////////////

var firstproduct = (from product in db.Products
where product.Category.CategoryName == “Beverages”
select product
).AsEnumerable().ElementAt(0);

Find number of rows in table using cursor in SQL

Regarding MSSQL,

Following code uses sys.objects table to retrieve ‘table names’, and running cursor on it to loop through each tables, then used system procedure ‘sp_executesql‘ to run a simple query to find number of records in it.

declare @tblname as nvarchar(200)
declare curForCount cursor for
select name from sys.objects where type=’u’ and name ‘sysdiagrams’

OPEN curForCount
fetch next from curForCount
into @tblname
WHILE @@FETCH_STATUS=0
BEGIN

declare @query nvarchar(1000);
set @query=’select ”’ + @tblname + ‘ — ” + cast(count(*) as nvarchar(20)) from ‘ + @tblname

exec sp_executesql @query

fetch next from curForCount
into @tblname
END
CLOSE curForCount
DEALLOCATE curForCount

 

Other Code stuff from Siddharth Borania:

LINQ queries with join in c#

https://siddharthboraniait.wordpress.com/2012/09/06/linq-query-in-csharp-asp-net-join