Postgres 按更改排序

Question

I am trying to change the order by ID in my Postgres questions database.

It is ordered randomly for some reason, but I want it to be ordered by ID ASC.

I am very new to postgres so I don't know what I am doing..,

I just want the result of this query:

SELECT * 
FROM public.questions
ORDER BY id ASC

but I don't know how to update my database with its order that shows the query output. It doesn't let me save it, I know im doing something wrong. How do I achieve it?

This is the current order, id goes like 1,2 then 4

I want it to look like this in perfect order by id 1,2,3,4

The reason why I want do this because I want my questions in my container to appear in order by ID, here my codes, any thoughts how i do achieve that?

class QuestionContainer extends React.Component {
  constructor() {
    super();
    this.state = {
      questions: [],
    };
    this.SubmitQuestion = this.SubmitQuestion.bind(this);
  }

  componentDidMount() {
    axios.get(`${env.url}/api/v1/en/questions?limit=100`).then((res) => {
      const qes = res.data.questions.map((a) => ({
        questionId: a.question_no,
        question: a.question,
      }));
      this.setState({ questions: qes });
    }, (err) => {
      console.log('Question fetch error ', err);
      this.setState({
        questions: [{
          questionId: 1,
          question: 'All',
        }],
      });
    });
  }

Answer 1

You always have to add ORDER BY if you want the result to be in a certain order.

Tables have a physical order, but in PostgreSQL that changes whenever you modify data, and even if you don't modify data you are not guaranteed to get the results in a certain order.

Answer 2

There's a few things:

1. when tuples are retrieved it is not guaranteed that they will be sorted in a consistent manner. They are compiled into a set for speed, which may be a random order. The way to enforce a sort order is to use the ORDER BY clause. Without it, there is no guarantee
2. I'd advise against using the id (primary key) as the ordered column. If order is important, I'd either add an order column to the table, or what I prefer is to have a timestamp field. In your case, though, it looks like question_no has a semantic order, so I might have used that over id .

3. your example looks like it's using JavaScript React; you can get the order from the database, or you can update the order in your presentation logic. Below I've used .sort((a,b)=>a.questionId - b.questionId) , which is a quick example:

    const qes = res.data.questions.map((a) => ({ questionId: a.question_no, question: a.question, })).sort((a,b)=>a.questionId - b.questionId);

4. If you wanted to try and retrieve it without the sort, I think you can pass an argument to the axios API. So this line:

    axios.get(`${env.url}/api/v1/en/questions?limit=100`)

   Would be changed to:

    axios.get(`${env.url}/api/v1/en/questions?orderBy=\\"question_no\\"&limit=100`)