Description:
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When trying to query a jsonb field in postgresql with the questionmark operator, we get error code 42601.

`$pdo->query("SELECT * FROM term_template tt WHERE (sites->0) ? 'site_id'");`

`"ERROR:  syntax error at or near "$1"
LINE 1: SELECT * FROM term_template tt WHERE (sites->0) $1 'site_id'..."`

See jsonb operators here: 

https://www.postgresql.org/docs/10/functions-json.html

The query works when executed within a database tool.

Test script:
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Fixture data in DB "sites" column:

[{"site_id": "example.org"}]