Hi, What is the best way to update a table on DB2 Z/os V9 from MS SQL server database table . Is it via a DB2 connect or a db2 client ? Would you like to share your experience in this regard please ?

I understand from this that you want to copy data from a MS SQLServer table to a DB2 z/OS table.
It all depends on the use case, when deciding for the "best way" to do this.
The easiest way for a large-volume data copy *could* be:
* save the table data into a CSV file,
* FTP that file to z/OS,
* load or insert the file data into the DB2 table.
All other scenarios will require you to write an MS-Windows application that connects to both databases (which requires the presence of DB2 connect, and of a DB2 client, on an MS-Windows server).