Derive Macro UpdateSync 

#[derive(UpdateSync)]
{
    // Attributes available to this derive:
    #[sql]
}

fn update_sync(&self, conn: &rusqlite::Connection) -> Result<bool, rusqlite::Error>

Generate fn for UPDATE with rusqlite, if there is a PRIMARY KEY.
PRIMARY KEY detection works only if constraint is in all caps, lowercase serves as escape hatch.

UPDATE {tab_name} SET {cols} WHERE {pk}=

#[derive(CreateTableSql,InsertSync,UpdateSync)]
struct Cat {
   #[sql(constraint = "PRIMARY KEY")]
   id: i64,
   name: String,
}
fn main() -> Result<(), rusqlite::Error> {
   let conn = rusqlite::Connection::open_in_memory()?;
   conn.execute_batch(Cat::CREATE_TABLE_SQL)?;

   let c = Cat {
      id: 0,
      name: "miau".to_owned(),
   };
   let id = c.insert_sync(&conn)?;
   assert!(id == 1);

   let c2 = Cat {
      id: 1,
      name: "meouw".to_owned(),
   };
   let ok = c2.update_sync(&conn)?;
   assert!(ok);

   Ok(())
}