Postgres 11

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create table test(data jsonb);

CREATE TABLE


insert into test(data) values(
'{"info":
[
	{
		"database": "Oracle",
		"company" : "Oracle"
	},
	{
		"database":"Sql Server",
		"company" :"Microsoft"
	},
	{
		"database":"DB2",
		"company" :"IBM"
	}
]
}'
)

INSERT 0 1


UPDATE test
SET data = jsonb_set(data, '{info}', (
  SELECT jsonb_agg(el || '{"License" : "Proprietary"}')
  FROM jsonb_array_elements(data -> 'info') el
))

UPDATE 1


select jsonb_pretty(data) from test


jsonb_pretty


{
    "info": [
        {
            "License": "Proprietary",
            "company": "Oracle",
            "database": "Oracle"
        },
        {
            "License": "Proprietary",
            "company": "Microsoft",
            "database": "Sql Server"
        },
        {
            "License": "Proprietary",
            "company": "IBM",
            "database": "DB2"
        }
    ]
}



SELECT 1