How to use LINQ expression to get a subset of data in VB.NET
In the article How LINQ expression is composed LINQ select clause was described. Web developer can change it to get a subset of data. For example, he/she could pull out a list of first name strings like this:
Dim matches = From client In clients _
select client.FirstName
or a list of strings with both first, middle and …
In the article How LINQ expression is composed LINQ select clause was described. Web developer can change it to get a subset of data. For example, he/she could pull out a list of first name strings like this:
var matches = from client in clients
select client.FirstName;
or a list of strings with both first, middle and last …
LINQ expressions have a superficial similarity to SQL queries, but the order of the clauses is rearranged.
All LINQ expressions must have a from clause that indicates the data source and a select clause that
indicates the data Web developer wants to retrieve (or a group clause that defines a series of groups into which the data should be placed). …
LINQ expressions have a superficial similarity to SQL queries, but the order of the clauses is rearranged.
All LINQ expressions must have a from clause that indicates the data source and a select clause that
indicates the data Web developer wants to retrieve (or a group clause that defines a series of groups into which the data should be placed). …
Web developer uses in this case the simplest form of LINQ – LINQ to Objects. Let for example Web developer has some sort of data class, like the Clients class shown next:
Public Class Client
Private _ClientID As Integer
Private _FirstName As String
Private _LastName As String
Private _TitleOfCourtesy As String
Public Sub Client(ByVal CliID As Integer, ByVal FName As String, _
Web developer uses in this case the simplest form of LINQ – LINQ to Objects. Let for example Web developer has some sort of data class, like the Clients class shown next:
public class Client
{
public int ClientID { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
Language Integrated Query (LINQ) is a set of language extensions for querying data. LINQ defines keywords that Web developer can use to select, filter, sort, group, and transform data. These keywords can work with different types of data. LINQ is a deeply integrated part of .NET, but it isn’t an ASP.NET-specific feature, and it can be used equally …
Web developer uses SQL Delete statement to remove one or more rows based on specified criteria:
DELETE FROM [table] WHERE [search_condition]
The following example removes a single matching row from the Clients table:
DELETE FROM Clients WHERE cli_id=’334-56-2289′
Note: If client record is linked to one or more records in other tables, for example ClientAccounts table, Web developer should delete linked records …
Web developer uses SQL Update statement to selects all the records that match a specified search expression and then to modify them all according to an update expression. At its simplest, the Update statement has the following format:
UPDATE [table] SET [update_expression] WHERE [search_condition]
Typically, the Update statement to is used to modify a single record. The following example adjusts …
Web developer can use the SQL Insert statement to add a new record to a table with the information he/she specifies:
INSERT INTO [table] ([column_list]) VALUES ([value_list])
Web developer can provide the information in any order he/she wants, as long as he/she makes sure the list of column names and the list of values correspond exactly:
INSERT INTO Clients (cli_id,cli_finame, …