PgSqlCommandBuilder Class

In This Topic

Automatically generates single-table commands used to reconcile changes made to a System.Data.DataSet with the PostgreSQL.

Syntax

Visual Basic
C#

'Declaration
 
Public Class PgSqlCommandBuilder 
   Inherits Devart.Common.DbCommandBuilder
   Implements System.ComponentModel.IComponent, System.IDisposable

public class PgSqlCommandBuilder : Devart.Common.DbCommandBuilder, System.ComponentModel.IComponent, System.IDisposable

Remarks

The PgSqlDataAdapter does not automatically generate the SQL statements required to reconcile changes made to a System.Data.DataSet associated with PostgreSQL. However, you can create a PgSqlCommandBuilder object that generates SQL statements for single-table updates. After assigning the PgSqlDataAdapter to the PgSqlCommandBuilder, it begins to generate any additional SQL statements that you do not set.

The relationship between a PgSqlDataAdapter and its corresponding PgSqlCommandBuilder is always one-to-one. To create this correspondence, you set the DataAdapter property of the PgSqlCommandBuilder object. This causes the PgSqlCommandBuilder to register itself as a listener, which produces the output of PgSqlDataAdapter.RowUpdating events that affect the System.Data.DataSet.

To generate INSERT, UPDATE, or DELETE statements, the PgSqlCommandBuilder uses the PgSqlDataAdapter.SelectCommand property to retrieve a required set of metadata. If you change the value of PgSqlDataAdapter.SelectCommand after the metadata has been retrieved (for example, after the first update), you then should call the Devart.Common.DbCommandBuilderBase.RefreshSchema method to update the metadata.

The PgSqlCommandBuilder also uses the Connection, CommandTimeout, and System.Data.Common.DbCommand.Transaction properties referenced by the PgSqlDataAdapter.SelectCommand. The user should call Devart.Common.DbCommandBuilderBase.RefreshSchema if any of these properties are modified, or value of the PgSqlDataAdapter.SelectCommand property itself is changed. Otherwise the PgSqlDataAdapter.InsertCommand, PgSqlDataAdapter.UpdateCommand, and PgSqlDataAdapter.DeleteCommand properties retain their previous values.

If you assign null to corresponding property of PgSqlDataAdapter, the PgSqlCommandBuilder will be disassociated from the PgSqlDataAdapter, and the generated commands will no longer be used.

Note: This class is not available in .NET Standard 1.3 compatible assembly. It is available only in the assembly for full .NET Framework and .NET Standard 2.0 compatible assembly.

Example

The following example uses PgSqlCommand, along with PgSqlDataAdapter and PgSqlConnection, to select rows from PostgreSQL. The example is passed an initialized System.Data.DataSet, a connection string, a query string that is SQL SELECT statement, and a string that is the name of the PostgreSQL table. The example then creates a PgSqlCommandBuilder.

csharp

public DataSet SelectPgSqlSrvRows(DataSet myDataSet,string pgConnection,string mySelectQuery,string myTableName)
{
  PgSqlConnection myConn = new PgSqlConnection(pgConnection);
  PgSqlDataAdapter myDataAdapter = new PgSqlDataAdapter();
  myDataAdapter.SelectCommand = new PgSqlCommand(mySelectQuery, myConn);
  PgSqlCommandBuilder pgCommandBuilder = new PgSqlCommandBuilder(myDataAdapter);

  myConn.Open();

  DataSet myDataSet = new DataSet();
  myDataAdapter.Fill(myDataSet, "Departments");

  //code to modify data in dataset here

  //Without the PgSqlCommandBuilder this line would fail
  myDataAdapter.Update(myDataSet, "Departments");

  myConn.Close();

  return myDataSet;
}

Visual Basic

Public Function SelectPgSqlSrvRows(myDataSet As DataSet, pgConnection As String, mySelectQuery As String, myTableName As String) As DataSet
  Dim myConn As New PgSqlConnection(pgConnection)
  Dim myDataAdapter As New PgSqlDataAdapter()
  myDataAdapter.SelectCommand = New PgSqlCommand(mySelectQuery, myConn)
  Dim pgCommandBuilder As PgSqlCommandBuilder = New PgSqlCommandBuilder(myDataAdapter)

  myConn.Open()

  Dim myDataSet As DataSet = New DataSet
  myDataAdapter.Fill(myDataSet, "Departments")

  ' Code to modify data in DataSet here

  ' Without the PgSqlCommandBuilder this line would fail.
  myDataAdapter.Update(myDataSet, "Departments")

  myConn.Close()

  SelectPgSqlSrvRows = myDataSet
End Function

Inheritance Hierarchy

System.Object
   System.MarshalByRefObject
      System.ComponentModel.Component
         System.Data.Common.DbCommandBuilder
            Devart.Common.DbCommandBuilderBase
               Devart.Common.DbCommandBuilder
                  Devart.Data.PostgreSql.PgSqlCommandBuilder

Reference

PgSqlCommandBuilder Members
Devart.Data.PostgreSql Namespace
PgSqlDataAdapter Class
PgSqlConnection Class
PgSqlCommand Class

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