'How to convert some columns to a JSON string (SQL)

I'm working with Amazon's Glue service and I need to convert some columns to a JSON string. Is this possible with a SQL query (more specifically spark SQL)?

Example Table

a | b | c

1a 2b 3c

Expected output:

a | json_string

1a '{"b":"2b", "c": "3c"}'

Sources

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Source: Stack Overflow

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