title: Copy data from a table and load it into another table
body: <p>I have a table 'A' having 40 columns. I need to copy the data from 20 specific columns from 'A' , to another table 'B' having those 20 columns. There will be around 3 - 10 million records.
  What will be the most efficient way to do this in PLSQL.  </p>