在查询中使用多个条件时出错

Question

I am working with PostgreSQL 8.4.4. I want to fetch record from table based on multiple conditions as,

1) check if record exists

2) if exists then -> if type_id is 1 then select name if type_id is 2 then select name, abbreviation

3) if record not exits then print as 'Missing'

Following is the query for the same

select 
    case 
        when exists (select NAME || ' ' || ABBREVIATION from CONTACTS_COMPANY where id = 15)
        then ( select
                case
                    when type_id = '1' 
                        then (select UPPER(NAME) from CONTACTS_COMPANY where id = 15) 
                    when type_id = '2' 
                        then (select UPPER(NAME) || ' ' || UPPER(ABBREVIATION) from CONTACTS_COMPANY where id = 15) 
                end
            ) 
    else UPPER('MISSING')
end

When firing above query I am getting error as

SQL error:

ERROR: column "type_id" does not exist

LINE 7: when type_id = '1'

I am not getting what exactly is causing error. Any help would be appreciated. Thanks in advance!

Answer 1

Assuming that "type_id" does in fact exist (you probably made sure of that..?), I would say that the query is not structured correctly. Your outermost select misses a "from" - statement. Furthermore, your inner statements are not correct. It should look something like this:

select 
    case 
        when exists  
           (select ('NAME' || ' ' || 'ABBREVIATION')
           from "CONTACTS_COMPANY")
        then (
            case
                when type_id = '1' 
                    then UPPER("NAME") 
                when type_id = '2' 
                    then  UPPER("NAME") || ' ' || UPPER("ABBREVIATION") 
            end
        ) 

    else UPPER('MISSING')
    end
from "CONTACTS_COMPANY"
WHERE id='15'

I haven't tested this, but the general structure should be ok. And I have hopefully understood correctly, what you are trying to do. Please post a comment, if that is not so :)

UPDATE code to working solution