How to insert values into mysql in vb3.5

[Jaynesh]

Could someone please tell me how to insert values into a table for php in vBulletin 3.5

i tried

INSERT INTO tablename VALUES ('$myvalue');

Nothing happened, no error message. just nothing.

i also tried

INSERT INTO " . TABLE_PREFIX . "mychat VALUES ('$message');

Nothing happened, no error message, just nothing.

What is the correct way of doing this in vBulletin 3.5