To copy data from account_invoice_line table in account module in PostgreSQL use this code in pgadmin and user can copy data from account_invoice_line table.
copy (SELECT *
INNER JOIN account_invoice ON account_invoice.id = account_invoice_line.invoice_id
account_invoice.state = 'open') to E'C:\\Users\\dinesh\\Documents\\demo\\inv_lines.csv' csv HEADER
C:\\Users\\dinesh\\Documents\\demo\\inv_lines.csv = this is rhe file location