how to insert and update data into postgresql from node js using if condition

i have to "UPDATE" data in postgresql if data is already present in database and "INSERT" i.e create a new user_Id and insert data using IF condition. i have tried with this but i am not getting output. please help me if you know .

 if(data.Details){
db.query('UPDATE Details SET fullName = $2,address= $3,phone = $4 WHERE user_id = $1 RETURNING *', [query, data.Details.fullName, data.Details.address, data.Details.phone],function(err,details) {
                 if (err) return callback(new Error('error'));
             })
}else{
db.query('INSERT INTO Details(user_id,fullName,address,phone) VALUES($1,$2,$3,$4) RETURNING *', [query, data.Details.fullName, data.Details.address, data.Details.phone],function(err,details) {
                                if (err) return callback(new Error('error'));

                            })
}

via katy