text: IF NOT EXISTS (
      SELECT 1
      FROM sys.columns
      WHERE
              Name = N'Birthday' AND
              Object_ID = Object_ID(N'client.Client')
  )
  BEGIN
  
      ALTER TABLE [client].[Client] ADD [Birthday] DATE NULL;
  
  END;
  
  IF NOT EXISTS (
      SELECT 1
      FROM sys.columns
      WHERE
            Name = N'Phone' AND
            Object_ID = Object_ID(N'client.Client')
  )
  BEGIN
  
      ALTER TABLE [client].[Client] ADD [Phone] NVARCHAR (32) NULL;
  
  END