连续多个条件（如果不存在）返回NULL postgresql

Question

I have a schema like:

[ad_id] .  [name] . [valueofname]
 1 .        name .    "brian"
 1 .        age  .    "23"
 2 .        job  .    "IT"
 2 .        name .    "Jack" 

the row name contains multiple values : age , name, birthday, job, age I'd like to convert it into this:

[ad_id] .      [name]  .       [age] .              [birthday] .    [job]
[valueofad_id][valueofname] [valueofnameofage] [valueofnameofbirth] [valueofnameofjob]

I did this query selection below to fix it , so in my program i must get the result where ad_id='xxxx' for each when name='name or age or birthday or job '

Some ad_id have not all the names , as you may see below the schema the ad_id= 1 has just the name and age but not the job so i want when the job not found it returns a NULL

 [ad_id] .  [name] . [valueofname]
  1 .        name .    "brian"
  1 .        age  .    "23"
  2 .        job  .    "IT"
  2 .        name .    "Jack" 


select ad_id,

max(case when name = 'name' and ad_id='xxx' then valueofname end) as name,
max(case when name = 'age' and ad_id='xxx'  then valueofname end) as age,
max(case when name = 'birthday' and ad_id='xxx' then valueofname end) as birthday,
max(case when name = 'job' and ad_id='xxx' then valueofname end) as job

from t
group by ad_id;

Answer 1

To flatten the records for all ad_ids, use:

select ad_id,
       max(case when name = 'name' then valueofname end) as name,
       max(case when name = 'age'then valueofname end) as age,
       max(case when name = 'birthday' then valueofname end) as birthday,
       max(case when name = 'job' then valueofname end) as job
from t
group by ad_id;

To get the results for a single ad_id, add a where clause:

select ad_id,
       max(case when name = 'name' then valueofname end) as name,
       max(case when name = 'age'then valueofname end) as age,
       max(case when name = 'birthday' then valueofname end) as birthday,
       max(case when name = 'job' then valueofname end) as job
from t
where ad_id = 'xxx' 
group by ad_id;

Note: If there are no rows with ad_id = 'xxx' then this will return no rows.