Using Mysql Json Array Field To Join On A Table In Knex Update

You can use the JSON_EXTRACT function in MySQL to extract a specific value from a JSON array stored in a column. Here’s an example using Knex to join a table based on a value in a JSON array:

javascript
knex.select('orders.*', 'customers.name')
  .from('orders')
  .join('customers', function() {
    this.on('orders.customer_ids', 'like', knex.raw("CONCAT('%', JSON_EXTRACT(customers.ids, '$[0]'), '%')"))
  })

In this example, we have a table called orders that contains a JSON array field called customer_ids, and we want to join it with a table called customers that has a column called ids that also contains JSON arrays.

The JSON_EXTRACT function is used to extract the first value ($[0]) from the customers.ids array, and the CONCAT function is used to add wildcards to the beginning and end of the resulting string, so that we can use the LIKE operator to match it with the orders.customer_ids field.

This should generate the following SQL statement:

sql
SELECT orders.*, customers.name
FROM orders
INNER JOIN customers ON orders.customer_ids LIKE CONCAT('%', JSON_EXTRACT(customers.ids, '$[0]'), '%')

Note that using JSON arrays in this way can make queries less efficient than using a traditional relational database schema, so it’s important to consider the trade-offs before using this approach.