Getting a syntax error even though query seems to have worked

[san bautista]

I am trying to add a field for a user to upload a logo to my membership page. I have everything working except for that I get a syntax error when I run my query.

Here is the error:

query failed: (1064) You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WHERE UserID='128'' at line 1

And here is my code:

if (!$mysqli->query("INSERT INTO mem_user (data) VALUES ('".$handle->file_dst_pathname."') WHERE UserID='".$user->userID."'"));
echo "query failed: (" . $mysqli->errno . ") " . $mysqli->error;

Now, I know I am doing something wrong with the apostrophes and quatation marks, but I dont know what. Ive tried every combination and it still gives the error. As you can see in the error, the query still runs, but fails to insert.

please help!