What is the most effective way to combine data entries with identical IDs into a unified entry?

Question

What is the most effective way to combine data entries with identical IDs into a unified entry?

My MySQL and Typeorm skills are at a beginner level. When I run my query, it returns data with duplicate IDs like:

[
  {
    id: "1",
    name: "john",
    place: "San Francisco"
  },
  {
    id: "1",
    name: "john",
    place: "Mumbai"
  }
]

What I'm looking for is to retrieve unique entries based on ID, such as:

[
 {
  id: "1",
  name: "john",
  place: ["San Francisco", "Mumbai"]
  }
]

I need help understanding how to use groupBy to achieve this desired result. Can anyone assist me?

mysql sql database typescript typeorm

Answer 1

Answer №1

While obtaining an array directly may not be possible, an alternative approach could involve utilizing group_concat. One potential query structure is as follows:

SELECT `id`, group_concat(`name`), group_concat(`place`) FROM <table_name> GROUP BY `id`

If individual names are not required to be concatenated

SELECT `id`, `name`, group_concat(`place`) FROM <table_name> GROUP BY `id`

In your code implementation, you can then split the resulting string into an array. The separator used can either be the default ',' or a custom one like '!#$!'

Answer 2

While obtaining an array directly may not be possible, an alternative approach could involve utilizing group_concat. One potential query structure is as follows:

SELECT `id`, group_concat(`name`), group_concat(`place`) FROM <table_name> GROUP BY `id`

If individual names are not required to be concatenated

SELECT `id`, `name`, group_concat(`place`) FROM <table_name> GROUP BY `id`

In your code implementation, you can then split the resulting string into an array. The separator used can either be the default ',' or a custom one like '!#$!'

Answer 3

Answer №2

To achieve the desired output in MySQL, you can utilize the GROUP_CONCAT function:

SELECT 
  id, name, GROUP_CONCAT(place) 
FROM 
  <table_name> 
GROUP BY 
  id

If you are working with TypeScript, you can make use of Array.prototype.reduce():

const data = [{id: "1",name: "john",place: "San Francisco"},{id: "1",name: "john",place: "Mumbai"}]

const dataHash = data.reduce((a, { id, name, place }) => {
  a[id] = a[id] || { id, name, place: [] } 
  a[id].place.push(place)
  return a
}, {})
const result = Object.values(dataHash)

console.log(result)

Answer 4

To achieve the desired output in MySQL, you can utilize the GROUP_CONCAT function:

SELECT 
  id, name, GROUP_CONCAT(place) 
FROM 
  <table_name> 
GROUP BY 
  id

If you are working with TypeScript, you can make use of Array.prototype.reduce():

const data = [{id: "1",name: "john",place: "San Francisco"},{id: "1",name: "john",place: "Mumbai"}]

const dataHash = data.reduce((a, { id, name, place }) => {
  a[id] = a[id] || { id, name, place: [] } 
  a[id].place.push(place)
  return a
}, {})
const result = Object.values(dataHash)

console.log(result)

What is the most effective way to combine data entries with identical IDs into a unified entry?

Answer №1

Answer №2

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