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

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

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

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

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

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

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

INSERT INTO suppliers
(supplier_id, supplier_name)
SELECT account_no, name
FROM customers
WHERE city = 'Newark';

SELECT count(*)
FROM customers
WHERE city = 'Newark';

INSERT INTO clients
(client_id, client_name, client_type)
SELECT supplier_id, supplier_name, 'advertising'
FROM suppliers
WHERE not exists (select * from clients
where clients.client_id = suppliers.supplier_id);

INSERT INTO clients
(client_id, client_name, client_type)
SELECT 10345, 'IBM', 'advertising'
FROM dual
WHERE not exists (select * from clients
where clients.client_id = 10345);

INSERT INTO Users( weight, desiredWeight )
  select val1 , val2  from tableXShoulatNotBeUsers
  WHERE somecondition;

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

Update Users set weight=160, desiredWeight=145  WHERE id = 1;

Replace Users set weight=160, desiredWeight=145  WHERE id = 1;

Note):- you should provide values to all fields else missed field in query
        will be set to null

create temporary table xtable ( weight int(11), desiredWeight int(11) ;

 insert into xtable (weight, desiredWeight)
    select weight, desiredWeight from Users where [condition]

 insert into Users (weight, desiredWeight)
    select weight , desiredWeight from xtable;

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

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

SELECT from Users WHERE id = 1;

UPDATE Users set (weight = 160, desiredWeight = 145) WHERE id = 1;

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

Consider INSERT INTO Users(name,email,weight, desiredWeight) VALUES (fred,bb@yy.com,160,145) WHERE name != fred AND email != bb@yy.com

INSERT INTO Test (id, name) VALUES (IF(1!=0,NULL,1),'Test');

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

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

mysql> INSERT INTO Users( weight, desiredWeight ) VALUES ( 160, 145 ) WHERE id = 1;
ERROR 1064 (42000): 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 id = 1' at line 1

... syntax to use near 'WHERE id = 1' ...

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

INSERT INTO Users(weight, desiredWeight )
select '$userWeight', '$userDesiredWeight'
FROM (select 1 a ) dummy
WHERE '$userWeight' != '' AND '$userDesiredWeight'!='';

INSERT into MyTable(aUser,aCar)
value(User123,Mini)

aUser   aCar
user123 mini
user123 HisOtherCarThatWasThereBefore

$sql="insert into ttable(username,password) values('$_POST[username]','$_POST[password]')";

INSERT INTO Users(weight, desiredWeight )
SELECT '$userWeight', '$userDesiredWeight'
FROM (select 1 a ) dummy
WHERE '$userWeight' != '' AND '$userDesiredWeight'!='';

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