How to search SQL column containing JSON array

For doing a search in a JSON array, one needs to use OPENJSON

DECLARE @table TABLE (Col NVARCHAR(MAX))
INSERT INTO @table VALUES ('{"names":["Joe","Fred","Sue"]}')

SELECT * FROM @table 
WHERE 'Joe' IN ( SELECT value FROM OPENJSON(Col,'$.names'))  

or as an alternative, one can use it with CROSS APPLY.

SELECT * FROM 
    @table 
    CROSS APPLY OPENJSON(Col,'$.names')
WHERE value ='Joe'

Postgres syntax

When you know the key that holds the data:

SELECT column_name from table_name where column_name->>'key' LIKE '%QUERYSTRING%';

When you don't know the key that holds the data:

SELECT column_name from table_name where column_name::text LIKE '%QUERYSTRING%';