we can store only single row items into database.
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I'm not clear on the question, but sounds like one of these scenarios:
1) You would like to store multiple rows but the process only stores one (verify your Write to Data Store Entity node is setup as 'Multiple' on the Data tab)
2) You would like to prevent more than 1 row from writing to the database (set the showWhen parameter of your Add Employee link to "count(ri!CDT)<1")