从一列中选择电话号码成多列sql

Question

I have a table called phones which I need to return the top three phone numbers, and three types for each c_no in six separate columns and then join to the contacts table. The phone table is laid out like so,

p_no,c_no, phone, p_type

My desired result set would be,

c_no, First_Phone, First_Phone_Type, Second_Phone, Second_Phone_Type, Third_Phone, Third_Phone_Type

I tried the following, but it doesn't show anything in the second or third columns when I add the group by c_no

select  c_no,
        (case when cp_sort = 1 and cp_status = 1 then phone end) as Phone_1,
        (case when cp_sort = 2 and cp_status = 1 then phone end) as Phone_2,
        (case when cp_sort = 3 and cp_status = 1 then phone end) as Phone_3
 from   phones cp  
 group by
         c_no

Thank you guys so much in advance for all the help!

Answer 1

You could try:

select distinct c_no, 
  (select phone from phones p1 where p0.c_no = p1.c_no and cp_sort = 1) Phone_1,
  (select phone from phones p2 where p0.c_no = p2.c_no and cp_sort = 2) Phone_2,
  (select phone from phones p3 where p0.c_no = p3.c_no and cp_sort = 3) Phone_3
from phones p0;

Might need some optimization to work well on a large set of data.