sql - If no result then another query, can be combined to one query? -

phone_book +----+---------+-----------+--------------+ | id | key     | code      |    value     | +----+---------+-----------+--------------+ | 1  | max_val | 111       |    reset     | +----+------+--------------+--------------+ | 2  | min_val | 222       |    set       | +----+------+--------------+--------------+ | 3  | min_val | 0         |    na        | +----+---------+-----------+--------------+ 

key , code combination primary key.

requirement:

if key , code present, return value.

if key present , code not exist return value of code 0.

implementation:

achieved using multiple query. syntax used jpql

1) "select param phone_book param upper(key)=:paramkey , code=:estcode";

if returns null, while shoot query

2) "select param phone_book param upper(key)=:paramkey , code=:o";

what looking :

can achieve in 1 query, or better way ?

thanks in advance.

in oracle sql, below suffice need. no need write plsql this.

select key,        nvl(code,0)                            -- make sure if code null value 0 phone_book   (key not null , code not null)  -- in fetching value when key , code present or ( key not null , code null);       -- in fetching value  when key present , code null.