ParentDataRelation Class

In This Topic

Establishes query-based master-detail relation.

Syntax

Visual Basic
C#

'Declaration
 
Public Class ParentDataRelation

public class ParentDataRelation

Remarks

The ParentDataRelation class is designed to establish a master-detail relationship where details data is not cached on the client. Every time the current position in the master table is changed, the client DbDataTable requests the appropriate portion of data from the server.

Use property ParentTable to specify master DbDataTable, and the properties ParentColumnNames and ChildColumnNames to describe the relationiship.

Note that this feature can be used only for two instances of DbDataTable class that have same DbDataTable.Owner. In other words, the DbDataTable objects must reside on the same forms.

Example

The following example shows how to render related data in two grids.

csharp

MySqlConnection connection = new MySqlConnection(
    "User Id=root;Host=localhost;Database=Test;");
connection.Open();
MySqlDataTable deptTable = new MySqlDataTable("SELECT * FROM dept", connection);
MySqlDataTable empTable = new MySqlDataTable("SELECT * FROM emp", connection);
empTable.ParentRelation.ParentTable = deptTable;
empTable.ParentRelation.ParentColumnNames = new string[] { "deptno" };
empTable.ParentRelation.ChildColumnNames = new string[] { "deptno" };
deptTable.Owner = this;
empTable.Owner = this;
deptTable.FetchAll = true;
empTable.FetchAll = true;
deptTable.Open();
empTable.Open();
deptDataGrid.DataSource = deptTable;
empDataGrid.DataSource = empTable;

Visual Basic

Dim connection As New MySqlConnection( _
    "User Id=root;Host=localhost;Database=Test;")
connection.Open()
Dim deptTable As New MySqlDataTable("SELECT * FROM dept", connection)
Dim empTable As New MySqlDataTable("SELECT * FROM emp", connection)
empTable.ParentRelation.ParentTable = deptTable
empTable.ParentRelation.ParentColumnNames = New String() {"deptno"}
empTable.ParentRelation.ChildColumnNames = New String() {"deptno"}
deptTable.Owner = Me
empTable.Owner = Me
deptTable.FetchAll = True
empTable.FetchAll = True
deptTable.Open()
empTable.Open()
deptDataGrid.DataSource = deptTable
empDataGrid.DataSource = empTable

Inheritance Hierarchy

System.Object
Devart.Common.ParentDataRelation

Requirements

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

ParentDataRelation Members
Devart.Common Namespace

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