default parameter for a mysql stored procedure|Optional Parameters in Stored Procedures

It's not possible for mysql side.
But, Try PassDault value from front end

Vb.net Module like

Imports MySql.Data.MySqlClient
Module MysqlRemainingParametersCollection
    'Add Remaining Parameter
       Public Function MysqlRemainingParameters(ByVal Cmd As MySqlCommand, ByVal ProcedureName As String)

        Dim dtProcedureParametersMas As New DataTable
        Try
            Try
                
                    If IsNothing(TotalProcedureParametersMainList) = False Then
                        dtProcedureParametersMas = DTFromRows(TotalProcedureParametersMainList, "SPECIFIC_NAME ='" & ProcedureName & "'")
                    Else
                        dtProcedureParametersMas = GetDataTable(CommandType.Text, "call SingleProcedureParameterCollect('" & SDBname & "','" & ProcedureName & "')")
                    End If


            Catch ex As Exception
            End Try
            If dtProcedureParametersMas.Rows.Count > 0 Then
                If dtProcedureParametersMas.Rows(0)("ROUTINE_TYPE") = "FUNCTION" Then
                    Return Cmd
                    Exit Function
                End If
            End If
            Dim fparameter As Boolean = False
            For i As Integer = 0 To dtProcedureParametersMas.Rows.Count - 1
                For j As Integer = 0 To Cmd.Parameters.Count - 1
                    If dtProcedureParametersMas.Rows(i)("Parameter_Name").ToString.ToUpper = Cmd.Parameters.Item(j).ToString.ToUpper Then
                        fparameter = True
                        If fparameter = True Then Exit For
                    Else
                        fparameter = False
                    End If
                Next
                If fparameter = False Then
                    If dtProcedureParametersMas.Rows(i)("Data_Type").ToString.ToUpper = "SMALLINT" Or _
                        dtProcedureParametersMas.Rows(i)("Data_Type").ToString.ToUpper = "TINYINT" Or _
                        dtProcedureParametersMas.Rows(i)("Data_Type").ToString.ToUpper = "DECIMAL" Or _
                        dtProcedureParametersMas.Rows(i)("Data_Type").ToString.ToUpper = "INT" Then
                        If dtProcedureParametersMas.Rows(i)("Parameter_Name").ToString.ToUpper = "$ISCANCELED" Then
                            Cmd.Parameters.Add(New MySqlParameter(dtProcedureParametersMas.Rows(i)("Parameter_Name").ToString, Nothing))
                        Else
                            Cmd.Parameters.Add(New MySqlParameter(dtProcedureParametersMas.Rows(i)("Parameter_Name").ToString, 0))
                        End If
                    Else
                        If dtProcedureParametersMas.Rows(i)("Parameter_Mode") = "INOUT" Then
                            Cmd.Parameters.Add(New MySqlParameter(dtProcedureParametersMas.Rows(i)("Parameter_Name").ToString, ""))
                        Else
                            Cmd.Parameters.Add(New MySqlParameter(dtProcedureParametersMas.Rows(i)("Parameter_Name").ToString, Nothing))
                        End If
                    End If
                End If
            Next
            'Add Remaining Prameter End

            'Set Direction inputOutput
            If dtProcedureParametersMas.Rows.Count > 0 Then
                For Each dr As DataRow In dtProcedureParametersMas.Select("Parameter_Mode='INOUT'")
                    If dtProcedureParametersMas.Select("Parameter_Mode='INOUT'").Length > 0 Then
                        Cmd.Parameters(dr.Item(0)).Direction = ParameterDirection.InputOutput
                    End If
                Next
            End If
            If dtProcedureParametersMas.Rows.Count > 0 Then
                For Each dr As DataRow In dtProcedureParametersMas.Select("Parameter_Mode='OUT'")
                    If dtProcedureParametersMas.Select("Parameter_Mode='OUT'").Length > 0 Then
                        Cmd.Parameters(dr.Item(0)).Direction = ParameterDirection.Output
                    End If
                Next
            End If
            'Set Direction inputOutput End
            Return Cmd
        Catch ex As Exception
            Return Nothing
            XtraMessageBox.Show(ex.Message)
        End Try
    End Function
End Module

Sample Coding:

sqlCmdOrigal.CommandText = "SP" & sEntryName

         With sqlCmdOrigal.Parameters

                            .Add(New MySqlParameter("$BranchCode", BranchCode))

                            .Add(New MySqlParameter("$VNo", Vno))

                            .Add(New MySqlParameter("$Ref_No", ""))

                            .Add(New MySqlParameter("$EntryDate", Format(deEntryDate.DateTime, "yyyy-MM-dd")))

                            .Add(New MySqlParameter("$USerCode", UserCode))

                            .Add(New MySqlParameter("$BankTransaction", 0))
.Add(New MySqlParameter("$Mode", 0))

       'MysqlRemainingParameters(Connectioninfo,ProcedureName)

                            .Add(New MySqlParameter("$SeasonHeadCode", dtFloorCashDet.Rows(iRow)("Season")))
'Add Remaining Parameter

          End with

sqlCmdOrigal = MysqlRemainingParameters(sqlCmdOrigal, sqlCmdOrigal.CommandText)
sqlCmdOrigal.ExecuteNonQuery()

sqlCmdOrigal.Parameters.Clear()

Initialy Load All Procedure Parameters into TotalProcedureParametersMainList  Variable(use login)

Public TotalProcedureParametersMainList As DataTable=nothing
TotalProcedureParametersMainList = GetDataTable(CommandType.Text, "call AllProcedureParameterCollect('" & SDBname & "')")

Procedure Samples:
All Procedure Parameter Collection

CREATE DEFINER=`root`@`%` PROCEDURE `allProcedureParameterCollect`(IN DbName varchar(100))
BEGIN
  SET @query = CONCAT('SELECT Parameter_Name,Data_Type,Parameter_Mode,ROUTINE_TYPE,SPECIFIC_NAME FROM information_schema.parameters 
      WHERE SPECIFIC_SCHEMA=''', DbName, ''';');
  PREPARE qry FROM @query;
  EXECUTE qry;
  DEALLOCATE PREPARE qry;
END

Single Procedure Parameter Collection

CREATE DEFINER=`root`@`%` PROCEDURE `SingleProcedureParameterCollect`(IN DbName varchar(100), IN ProcedureName varchar(100))
BEGIN
  SET @query = CONCAT('SELECT Parameter_Name,Data_Type,Parameter_Mode,ROUTINE_TYPE FROM information_schema.parameters 
      WHERE SPECIFIC_SCHEMA=''', DbName, ''' and SPECIFIC_NAME = ''', ProcedureName, ''';');
  PREPARE qry FROM @query;
  EXECUTE qry;
  DEALLOCATE PREPARE qry;
END