C# For Loop in Transaction but no data is inserted

Question

You need to call trans.Complete(); at some point in your code. Otherwise the transaction is rolled back.

public int addBulkLeadStages(List<LeadStage> allLeadStages)
{
    //throw new NotImplementedException();
    SqlConnection connection;
    SqlCommand cmd;
    int effectedRows = 0;
    int rowsCount = 0;
    int updatedRowsCount = 0;
    using (TransactionScope trans = new TransactionScope())
    {
        using (connection = new SqlConnection(SalesForceDBManager.getConnectionString(SalesForceDB.CONNECTION_STRING)))
        {
            //Open Connection
            connection.Open();                
            //Craete Command
            cmd = connection.CreateCommand();
            int noOfLeadStages = allLeadStages.Count;
            for (int i = 0; i < noOfLeadStages; i++)
            {
                //Check If entry already available
                if (isLeadStageRecordExist(allLeadStages[i].ID,connection))
                {
                    //Update Existing Record
                    updatedRowsCount = updateLeadStage(connection, allLeadStages[i].ID, allLeadStages[i]);
                }
                else
                {
                    cmd.CommandText = "INSERT INTO " + SalesForceDB.LeadStage.TABLE_LEAD_STAGE + "(" +
                        SalesForceDB.LeadStage.COLUMN_ID + "," + SalesForceDB.LeadStage.COLUMN_NAME + "," +
                        SalesForceDB.LeadStage.COLUMN_COMMENTS_REMARKS + "," + SalesForceDB.LeadStage.COLUMN_ENTRY_POINT + "," +
                        SalesForceDB.LeadStage.COLUMN_EXIT_POINT + "," + SalesForceDB.CommonColumns.COLUMN_IS_ACTIVE + "," +
                        SalesForceDB.LeadStage.COLUMN_SEQUENCE_NO + "," + SalesForceDB.LeadStage.COLUMN_STAGE_DESCRIPTION + "," +
                        SalesForceDB.CommonColumns.COLUMN_CREATED_BY + "," + SalesForceDB.CommonColumns.COLUMN_CREATED_DATE + "," +
                        SalesForceDB.CommonColumns.COLUMN_LAST_MODIFIED_BY + "," + SalesForceDB.CommonColumns.COLUMN_LAST_MODIFIED_DATE + ")" +
                        " VALUES (@ID,@StageName,@CommentsRemarks,@EntryPoint,@ExitPoint,@IsActive,@SequenceNo,@StageDesc,@CreatedBy,@CreatedDate," +
                        "@LastModifiedBy,@LastModifiedDate)";

                    //Adding Command Parameters
                    cmd.Parameters.AddWithValue("@ID", allLeadStages[i].ID);
                    cmd.Parameters.AddWithValue("@StageName", allLeadStages[i].Name);
                    cmd.Parameters.AddWithValue("@CommentsRemarks", allLeadStages[i].Comments);
                    cmd.Parameters.AddWithValue("@EntryPoint", allLeadStages[i].EntryPoint);
                    cmd.Parameters.AddWithValue("@ExitPoint", allLeadStages[i].ExitPoint);
                    cmd.Parameters.AddWithValue("@IsActive", allLeadStages[i].IsActive);
                    cmd.Parameters.AddWithValue("@SequenceNo", allLeadStages[i].SequenceNo);
                    cmd.Parameters.AddWithValue("@StageDesc", allLeadStages[i].Description);
                    cmd.Parameters.AddWithValue("@CreatedDate", allLeadStages[i].CreatedDate);
                    cmd.Parameters.AddWithValue("@CreatedBy", allLeadStages[i].CreatedBy);
                    cmd.Parameters.AddWithValue("@LastModifiedBy", allLeadStages[i].LastModifiedBy);
                    cmd.Parameters.AddWithValue("@LastModifiedDate", allLeadStages[i].LastModifiedDate);
                    //Execute query
                    effectedRows = cmd.ExecuteNonQuery();
                    rowsCount += effectedRows;
                    cmd.Parameters.Clear();
                }
            }

            trans.Complete(); // <-- THIS IS MISSING!
        }
        return rowsCount;
    }
}