Section 340 cr. p. c. procedure

Dear all,
Please let me know that there is any need to record the statement of
the complainant under oath in preliminary investigation u/s 340 Cr. p.C. if the
complainant already filed the complaint u/s 340 r/w section 195 Cr. p.C.
supported by affidavit.

Also suggest me the procedure of preliminary investigation u/s 340 Cr P.C. and
relevant ruling of SC. I hav hearing tom. please suggest me urgently.

Sunil Kumar