MySqlText Class

In This Topic

Represents a variable-length stream of characters to be stored in or retrieved from the database.

Syntax

Visual Basic
C#

'Declaration
 
Public Class MySqlText 
   Inherits MySqlBlob
   Implements System.Data.SqlTypes.INullable, System.ICloneable, System.IComparable, System.IDisposable, System.Xml.Serialization.IXmlSerializable

public class MySqlText : MySqlBlob, System.Data.SqlTypes.INullable, System.ICloneable, System.IComparable, System.IDisposable, System.Xml.Serialization.IXmlSerializable

Remarks

Use this class to retrieve text blocks stored in BLOB files. MySqlText suits best for TINYTEXT, TEXT, MEDIUMTEXT, and LONGTEXT column types.

Typically you use ToString method and Value property to retrieve strings from MySqlText. However, you can treat MySqlText as stream of bytes and decode it yourself.

When creating a MySqlText instance, default client charset is used unless you explicitly force it to be UTF8 by setting unicode parameter to true in constructor MySqlText.New(string,bool)

When obtaining a MySqlText object from server, its encoding depends on Unicode property of MySqlConnection opened. If this property is true, UTF8 client charset is used, otherwise MySqlText uses encoding default for your system.

When sending data to server, MySqlText encoding must be synchronised with MySqlConnection encoding. If they differ, data sent to the server will be incorrect.

Example

This sample code consists of two routines. The first uploads a string to the server, while the second retrieves all strings contained in "BlockContent" column of the table.

csharp

public void UploadSqlText(MySqlConnection myConnection)
{
  myConnection.Unicode = true;
  MySqlText myTextSql = new MySqlText("This is a test text block");
  MySqlCommand myCommand = new MySqlCommand("INSERT INTO Test.TextBlocks (BlockID, BlockName, BlockContent) VALUES(1,'First',:BlockText)", myConnection);
  myCommand.Parameters.Add("BlockText",myTextSql);
  myConnection.Open();
  try
  {
    Console.WriteLine(myCommand.ExecuteNonQuery()+" rows affected.");
  }
  finally
  {
    myConnection.Close();
  }
}                                                                                                                   

public void DownloadSqlText(MySqlConnection myConnection)
{
  myConnection.Unicode = true;
  MySqlCommand myCommand = new MySqlCommand("SELECT * FROM Test.TextBlocks", myConnection);
  myConnection.Open();
  MySqlDataReader myReader = myCommand.ExecuteReader(CommandBehavior.Default);
  try
  {
    while (myReader.Read())
    {
      MySqlText myTextSql = myReader.GetMySqlText(myReader.GetOrdinal("BlockContent"));
      if(!myTextSql.IsNull)
      {
        Console.WriteLine(myTextSql.Value);
      }
    }
  }
  finally
  {
    myReader.Close();
    myConnection.Close();
  }
}

Visual Basic

Public Sub UploadSqlText(ByVal myConnection As MySqlConnection)
  myConnection.Unicode = True
  Dim myTextSql As MySqlText = New MySqlText("This is a test text block")
  Dim myCommand As MySqlCommand = New MySqlCommand("INSERT INTO Test.TextBlocks (BlockID, BlockName, BlockContent) VALUES(3,'First',:BlockText)", myConnection)
  myCommand.Parameters.Add("BlockText", myTextSql)
  myConnection.Open()
  Try
    Console.WriteLine(String.Concat(myCommand.ExecuteNonQuery(), " rows affected."))
  Finally
    myConnection.Close()
  End Try
End Sub

Public Sub DownloadSqlText(ByVal myConnection As MySqlConnection)
  myConnection.Unicode = True
  Dim myCommand As New MySqlCommand("SELECT * FROM Test.TextBlocks", myConnection)
  myConnection.Open()
  Dim myReader As MySqlDataReader = myCommand.ExecuteReader(CommandBehavior.Default)
  Try
    While myReader.Read()
      Dim myTextSql As MySqlText = myReader.GetMySqlText(myReader.GetOrdinal("BlockContent"))
      If Not myTextSql.IsNull Then
        Console.WriteLine(myTextSql.Value)
      End If
    End While
  Finally
    myReader.Close()
    myConnection.Close()
  End Try
End Sub

Inheritance Hierarchy

System.Object
   System.MarshalByRefObject
      System.IO.Stream
         Devart.Data.MySql.MySqlBlob
            Devart.Data.MySql.MySqlText

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

MySqlText Members
Devart.Data.MySql Namespace
MySqlBlob Class

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