How to search for text in an array of varchar field in Presto?

Question

A field is defined to be array(varchar) in modeanlyatic.

I want to search for records with field contains a certain text pattern, says 'ABCD' .

If I run this SQL:

select * from data_table 
where top_results like '%ABCD%'

It throws this error:

Query failed (#20190730_021145_23663_dn9fj): line 2:7: Left side of LIKE expression must evaluate to a varchar (actual: array(varchar)

What is the correct syntax to detect the presence of a certain string?

Answer 1

Use filter(array(T), function(T, boolean)) -> array(T)

This function returns array containing elements for which function returns true. Use cardinality function to check if array is not empty:

SELECT cardinality(filter(ARRAY ['123ABCD456', 'DQF', 'ABCD', 'ABC'], x -> x like '%ABCD%'))>0 ;

Returns

true

Check another value:

SELECT cardinality(filter(ARRAY ['123ABCD456', 'DQF', 'ABCD', 'ABC'], x -> x like '%XXX%'))>0 ;

Returns

false

Hope you got the idea.

Answer 2

Convert it to a json string and then search the string

json_format(cast(top_results as JSON))

select * from data_table 
where json_format(cast(top_results as JSON)) like '%ABCD%'