MySQL Insert query doesn't work with WHERE clause

MySQL INSERT Syntax does not support the WHERE clause so your query as it stands will fail. Assuming your id column is unique or primary key:

If you're trying to insert a new row with ID 1 you should be using:

INSERT INTO Users(id, weight, desiredWeight) VALUES(1, 160, 145);

If you're trying to change the weight/desiredWeight values for an existing row with ID 1 you should be using:

UPDATE Users SET weight = 160, desiredWeight = 145 WHERE id = 1;

If you want you can also use INSERT .. ON DUPLICATE KEY syntax like so:

INSERT INTO Users (id, weight, desiredWeight) VALUES(1, 160, 145) ON DUPLICATE KEY UPDATE weight=160, desiredWeight=145

OR even like so:

INSERT INTO Users SET id=1, weight=160, desiredWeight=145 ON DUPLICATE KEY UPDATE weight=160, desiredWeight=145

It's also important to note that if your id column is an autoincrement column then you might as well omit it from your INSERT all together and let mysql increment it as normal.

You can't combine a WHERE clause with a VALUES clause. You have two options as far as I am aware-

1. INSERT specifying values

   INSERT INTO Users(weight, desiredWeight) 
   VALUES (160,145)
   

2. INSERT using a SELECT statement

   INSERT INTO Users(weight, desiredWeight) 
   SELECT weight, desiredWeight 
   FROM AnotherTable 
   WHERE id = 1
   

You use the WHERE clause for UPDATE queries. When you INSERT, you are assuming that the row doesn't exist.

The OP's statement would then become;

UPDATE Users SET weight = 160, desiredWeight = 45 where id = 1;

In MySQL, if you want to INSERT or UPDATE, you can use the REPLACE query with a WHERE clause. If the WHERE doesn't exist, it INSERTS, otherwise it UPDATES.

EDIT

I think that Bill Karwin's point is important enough to pull up out of the comments and make it very obvious. Thanks Bill, it has been too long since I have worked with MySQL, I remembered that I had issues with REPLACE, but I forgot what they were. I should have looked it up.

That's not how MySQL's REPLACE works. It does a DELETE (which may be a no-op if the row does not exist), followed by an INSERT. Think of the consequences vis. triggers and foreign key dependencies. Instead, use INSERT...ON DUPLICATE KEY UPDATE.