How can a left join update be done with Python and JSON arrays?

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It is not possible to perform a left join update directly on JSON arrays using Python. JSON arrays are simply lists of dictionaries and do not have any built-in functionality for database operations.

However, you can use Python to perform the join and update operation manually by looping through the two arrays, matching the rows on a common key, and updating the values accordingly. Here is an example:

import json

# Sample data
left_data = [{'id': 1, 'name': 'Alice', 'age': 25},
             {'id': 2, 'name': 'Bob', 'age': 30},
             {'id': 3, 'name': 'Charlie', 'age': 35}]
right_data = [{'id': 1, 'city': 'New York'},
              {'id': 2, 'city': 'San Francisco'}]

# Perform left join update on 'id' field
for left_row in left_data:
    for right_row in right_data:
        if left_row['id'] == right_row['id']:
            left_row.update(right_row)

# Output updated left_data
print(json.dumps(left_data, indent=4))

In this example, we have two JSON arrays left_data and right_data. We perform a left join update on the id field by looping through each row in the left array and searching for a matching row in the right array. If a match is found, we update the values in the left row with the values from the right row.

The resulting left_data array will contain the original data from left_data with the additional city field from right_data added where applicable.