ParentDataRelation Class

In This Topic

Syntax
Remarks
Example
Inheritance Hierarchy
See Also

Establishes query-based master-detail relation.

Syntax

Visual Basic
C#

public class ParentDataRelation

'Declaration
 
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

PgSqlConnection connection = new PgSqlConnection(
    "host=server;database=test;user id=postgres;");
connection.Open();
PgSqlDataTable deptTable = new PgSqlDataTable("SELECT * FROM dept", connection);
PgSqlDataTable empTable = new PgSqlDataTable("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 PgSqlConnection( _
    "host=server;database=test;user id=postgres;")
connection.Open()
Dim deptTable As New PgSqlDataTable("SELECT * FROM dept", connection)
Dim empTable As New PgSqlDataTable("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

Reference

ParentDataRelation Members
Devart.Common Namespace

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