public boolean ParseQuery(Scanner s) {
    if(!consumeToken(s,"SELECT"){return false;}
    if(!consumeToken(s,"*"){return false;}
    if(s.hasNext("FROM")){
         s.next();
         if(!parseName(s)){return false;}
    }
    if(s.hasNext("WHERE")){
         s.next();
         if(!parseName(s)){return false;}
         if(!consumeToken(s,"=")){return false;}
         if(!parseData(s)){return false;}
    }
    if(!consumeToken(s,";"){return false;}
    return true;
}

public boolean parseName(Scanner s){
    return consumeToken(s,"[A-Za-z]+");
}

public boolean parseData(Scanner s){
    return consumeToken(s, "[A-Za-z0-9]+");
}

public boolean consumeToken(Scanner s, String token){
    if(s.hasNext(token){
        s.next();
        return true;
    }
    return false;
}