Postgresql更新

Question

I am new to postgreql and sql itself.So how do I set a json value of 'class'? Official documentation and other resources provided me with the function jsonb_set which i used to set a hard coded value of '"X"', however I am not able to set a dynamic value based off of the student table's column.

update dp_user_custom_properties_v2 ducpv
    set json_value = jsonb_set(ducpv.json_value, '{class}',s.class::text)
    from students s
    where s.user_id = ducpv.user_id and s.status is null;

this doesn't work but

set json_value = jsonb_set(ducpv.json_value, '{class}','"A"')

this does.

Answer 1

This is happening because 3rd argument of jsonb_set() should be a jsonb and you are passing text. You should convert it to jsonb first. Use to_jsonb() like below.

update dp_user_custom_properties_v2 ducpv
    set json_value = jsonb_set(ducpv.json_value, '{class}',to_jsonb(s.class::text))
    from students s
    where s.user_id = ducpv.user_id and s.status is null;

Answer 2

I found another way of doing it looking thorugh online resources -

update dp_user_custom_properties_v2 ducpv
                        set json_value = ducpv.json_value||jsonb_build_object('section', s.section,'class', s.class)
                        from students s
                        where s.user_id = ducpv.user_id and s.status is null;