@Naveena G :
The error in your SQL query may be caused by the fact that the transform function expects an array or map as its first argument, but you are passing a string instead. In this case, the Subject column appears to contain an array, but you are not specifying which element of the array to apply the data_hide function to. Assuming that you want to apply the data_hide function to each element of the Subject array separately, you can modify your query as follows:
SELECT id, transform(Subject, x -> data_hide(x)) AS new_data FROM my_table
However, if you only want to apply the data_hide function to the entire Subject array if the user is not a member of the groupName group, you can modify your query as follows:
SELECT id, IF(is_member('groupName'), Subject, transform(Subject, x -> data_hide(x))) AS new_data FROM my_table
This will return the original Subject array if the user is a member of the groupName group, otherwise it will apply the data_hide function to each element of the array.