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First - select the data in a variable type var.
Below two example of the selectusing lingQ
Unique table, read all fields
var query = from vep in dataset.Tables["name_my_table"].AsEnumerable()
where (Int16)vep["field1"] == Convert.ToInt16(search_parameter_1)
&& (string)vep["field2"] == search_parameter_2
two tables with join, read some fields and field ordinate
var query = from lan in dataset.Tables["name_my_table1"].AsEnumerable()
join noc in dataset.Tables["name_my_table2"].AsEnumerable()
on (string)lan["id"] equals (string)pap["id"]
where (int)noc["id"] >0orderby noc["date"]
data = ((DateTime)noc["date"]).ToString("dd/MM/yyyy")
num = noc["field1"].ToString()
qtd = lan["field1"].ToString()
val = ((decimal)lan["value"]).ToString("0,0.00")
Second - Create a datatable with the selected data
datatable dt = new datatable();
Example 1foreach (var item in query)
dr = dt.NewRow();
dr["data"] = item.vep["field1"].toString();
dr["num"] = item.vep["field2"].toString();
dr["qtd"] = item.vep["field3"].toString();
dr["val_unitario"] = item.vep["field4"].toString();
Example 2foreach (var item in query)
dr = dt.NewRow();
dr["data"] = item.data;
dr["num"] = item.num;
dr["qtd"] = item.qtd;
dr["val_unitario"] = item.val;
Third - Display in grid
my_grid.DataSource = dt;
I hope has been helping.
GreaterThan() and LessThan() methods won't work on strings. Why? It's simple. String is not numeric value!
To be able to compare lowValueString and highValueString with the set of numbers, you need to convert string values into proper data type. Convertion should be made before you data into Between method.
I got the following error "The connection was not closed. The connection's current state is connecting entity framework" while implementing Async/Await functionality in single transaction scope. Please provide the suggestions to resolve the issue.
The problem is the entity framework automatically opens and closes a connection with each call to the database, thus when using a transaction, you are attempting to spread a transaction out over multiple connections which elevates to MSDTC.
Open the connection manually and close it when you are done. Then the framework will use only one connection for all your calls.
I have a 20 records in a database table. Each record has and ID. I want to read a field in each record fieldA. I only want to read the records that have an ID '1'. For each record that has an ID '1' and fieldA Is Not Null I want to return a count of those records.
So if 10 records have data in fieldA and have ID '1' then my count for fieldA will be 10.
If you're using LINQ, it depends which database you're targetting. If you were using the old ODBC ways of accessing databases, there was a set of metadata queries that you could perform that were nice and generic - however, as you are using L2S, the method depends on the database provider. For instance, in SQL Server, you could use
SELECT [FieldList goes here] FROM information_schema.Tables
Last Visit: 31-Dec-99 18:00 Last Update: 25-Jun-17 15:58